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4.9L swap A/C hookup questions. by Dennis LaGrua
Started on: 08-28-2014 10:09 AM
Replies: 15 (433 views)
Last post by: Raydar on 09-17-2014 06:34 PM
Dennis LaGrua
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Report this Post08-28-2014 10:09 AM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
The 4.9L when installed in a Cadillac uses the BCM for A/C control with a number of temp switches and a low side pressure switch. When you swap this engine, a new A/C control scheme must be used. You could use the Fiero control loop and the Fiero A/C compressor (as this will give you all the control switches) but my swap will use the Cadillac compressor. The logical way (as I see it) is to use the Fiero electrical loop with the low pressure switch on the accumulator but doing this does not provide the system with a high side safety switch. I may be able to adapt the std GM three wire Refrigerant pressure switch or maybe not but here is the question.
Is anyone aware of a simple two wire A/C high side safety switch that I can use so that the system is protected? I figure that I could splice it in series with the A/C relay so that the compressor clutch will turn off if high side pressures exceed what is safe.
What are you 4.9L engine swap guys doing for A/C control?

Update: I believe that Ford used an external high pressure sensor but more research is required before we use it.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 08-28-2014).]

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Raydar
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Report this Post08-28-2014 09:07 PM Click Here to See the Profile for RaydarClick Here to Email RaydarSend a Private Message to RaydarEdit/Delete MessageReply w/QuoteDirect Link to This Post
The 4.9, as installed by the Fiero Factory (like mine) has no provision for high pressure cutoff. It works exactly as you described.

I'm in the process of rebuilding my system after a compressor failure. I figure that the easiest way to incorporate a high pressure cutoff is to install a switch on the high side service port in the front compartment, and wire it in series with the pressure cycling switch on the accumulator.
The problem is finding the appropriate switch. Seems like I heard that Dodge uses something like this, but I don't have any part numbers or anything.

If you have a method that will work better, or is simpler, I'm certainly open to suggestions.
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deanearl
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Report this Post08-28-2014 10:22 PM Click Here to See the Profile for deanearlSend a Private Message to deanearlEdit/Delete MessageReply w/QuoteDirect Link to This Post
Checkout vintageair, they have safety switches and the fittings. That's what I am going to use on mine.
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Dennis LaGrua
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Report this Post08-29-2014 09:24 AM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by deanearl:

Checkout vintageair, they have safety switches and the fittings. That's what I am going to use on mine.


Will check that out. Four Seasons also manufactures a variety of pressure sensors but some of them are four terminal (with the fan function) while others are 3 terminal, set up to put out a 5V variable signal that is compatible with modern PCM's . The 4.9L A/C system needs a simple normally closed high pressure switch that will open when maximum pressures are exceeded. Dodge trucks and some Ford vehicles used these tow terminal switches. I will investigate and post the results later today.
UPDATE: Standard P/N PCS122 is a two terminal A/C (advertised as High side
pressure switch that will attach to an A/C switch port. Its used on 90's Ford vehicles. If we can get the specs on this switch this would be perfect. Its about $15-$20 but we would need to aluminum braze the fitting on the high side line and put it in series with the low side cut off switch as pointed out. I just might order one and try it when the time comes to make up the lines. I read a while back that the standard Fiero A/C hose casn fit the Cadillac compressor and the Fiero firewall manifold attachment points with a simple re-bend but have not gotten this far in the swap as yet.
Here on that should work but it may not be 2 terminal. Four Seasons 36490. This should be a high side cut off switch but 4 terminals???.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 08-29-2014).]

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Raydar
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Report this Post08-29-2014 05:20 PM Click Here to See the Profile for RaydarClick Here to Email RaydarSend a Private Message to RaydarEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Dennis LaGrua:
... Standard P/N PCS122 is a two terminal A/C advertised as High side pressure switch...


I Googled that part number. Nearly all the results show it as a low pressure switch.

I'm looking, too.
There are several different Four Seasons part numbers. 36490, 36493, 36495, 36498.

Edit - 36498 looks to have only two pins. Now, if it will fit on my high side port without adding another fitting...

[This message has been edited by Raydar (edited 08-29-2014).]

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Dennis LaGrua
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Report this Post08-29-2014 09:23 PM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Raydar:


I Googled that part number. Nearly all the results show it as a low pressure switch.

I'm looking, too.
There are several different Four Seasons part numbers. 36490, 36493, 36495, 36498.

Edit - 36498 looks to have only two pins. Now, if it will fit on my high side port without adding another fitting...


Four seasons 36498 looks like it may work but you would have to add an inline pressure port to the high side line. The threads may be metric (10MM is common for GM) or they could be SAE threads. Ive seen crimp on fittings for #8 barrier hose on ebay with the switch ports but you can also buy the switch port nipples and braze them on the aluminum parts of the high side lines.
This source lists the switch port nipples in aluminum.
http://www.apairinc.com/detail.asp?Part=451-462 This is what I used on my 3800SC swap but my refrigerant pressure switch is the 3 pin 5V output one that interfaces with the PCM.
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racingfortheson
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Report this Post08-30-2014 01:21 AM Click Here to See the Profile for racingforthesonSend a Private Message to racingforthesonEdit/Delete MessageReply w/QuoteDirect Link to This Post
Wait wait... I thought you could just use the fiero compressor.
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Dennis LaGrua
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Report this Post08-30-2014 11:20 AM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by racingfortheson:

Wait wait... I thought you could just use the fiero compressor.


I do not believe that the Fiero compressors will bolt in without modifications and its possible that the Cadillac compressor may be of larger displacement for more efficient cooling. There are also no provisions for the safety switch on the rear of the Cadillac compressor. RegardIess, I found a brand new Cadillac compressor for a very good price and bolted it right in place. On the engine swaps that I have done I have used the A/C compressor that came with the engine.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

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Raydar
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Report this Post08-30-2014 12:08 PM Click Here to See the Profile for RaydarClick Here to Email RaydarSend a Private Message to RaydarEdit/Delete MessageReply w/QuoteDirect Link to This Post
The compressors are similar, in that they are both HR6 pieces (at least the 88 Fiero is), but I never tried to bolt a Fiero compressor in place on the 4.9.
There are some brackets used that are different, and I'm not sure about the clocking of the end caps (heads).
The main thing is that the pulleys/clutches are different. Probably not a big deal if you have the right tools to change them, but most people probably don't. You might be able to change the rear head, to one that incorporates the switches, but it would probably void any warranty on a new compressor.

Aside from that, there's no substitute for knowing what you're doing. And I don't. A/C compressors (and automatic transmissions) are little boxes full of sorcery and witchcraft, as far as I'm concerned.
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Report this Post08-30-2014 03:48 PM Click Here to See the Profile for FieroseverywhereClick Here to Email FieroseverywhereSend a Private Message to FieroseverywhereEdit/Delete MessageReply w/QuoteDirect Link to This Post
When you guys figure out the fittings and pressure switch you should add your results to the first post of this thread. It will make a great reference for other 4.9 swappers, especially with your title.

Hmm. I have access to a crimping machine. Theoretically, is someone were to find the right fittings, know their needed hose length, and need a hose made up I may be able to help out in that area....

I can get any kind of hose needed and we order from aeroquip quite often. Hmmm... self sealing quick release couplings for easier install and cradle drop....

[This message has been edited by Fieroseverywhere (edited 08-30-2014).]

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Dennis LaGrua
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Report this Post08-30-2014 07:43 PM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
This might offer a solution IF the switch that we decide to use has 10mm threads. The price is very high though.
http://www.ebay.com/itm/8-B...em418607c096&vxp=mtr

The Four Seasons P/N 36498 is in a high side safety switch and it is two wire. Its specs are 300 PSI ON and 475 PSI OFF which is a bit on the high side. The other switches called out in Radars post all cutoff at 430 PSI (which IMO is better) but I am not sure that they are two wire. Some switches have extra pins for cooling fan contacts.

[This message has been edited by Dennis LaGrua (edited 08-31-2014).]

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Raydar
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Report this Post09-15-2014 07:54 PM Click Here to See the Profile for RaydarClick Here to Email RaydarSend a Private Message to RaydarEdit/Delete MessageReply w/QuoteDirect Link to This Post
I found a solution to my situation.

I picked up my new compressor today. It's a Comfort Temp P/N 6511358. (Came from a local radiator and a/c repair shop.)
It's a new compressor, sold as a replacement for the Caddy 4.9. Price was $280. A good deal for a new compressor, compared to others that I've seen.
The "solution" is the fact that, instead of using a blank casting, it has dummy plugs in the rear compressor head, which can be removed and replaced with whatever switches you want to install.
I just plan to get a standard replacement high pressure switch, and the appropriate connector, and wire it in series with the clutch.

This may not be the ideal solution if you don't need a compressor, but since my old compressor was a doorstop anyway, it's perfect for me.

Edit - Googled "Comfort Temp 6511358" and found nothing.
eBay, however, has Cadillac compressors with that same part number under the Global brand name, for under $200. Don't know if they're the same or not. I didn't find any pics of the rear head.

[This message has been edited by Raydar (edited 09-15-2014).]

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Dennis LaGrua
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Report this Post09-15-2014 08:17 PM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Raydar:

I found a solution to my situation.

I picked up my new compressor today. It's a Comfort Temp P/N 6511358. (Came from a local radiator and a/c repair shop.)
It's a new compressor, sold as a replacement for the Caddy 4.9. Price was $280. A good deal for a new compressor, compared to others that I've seen.
The "solution" is the fact that, instead of using a blank casting, it has dummy plugs in the rear compressor head, which can be removed and replaced with whatever switches you want to install.
I just plan to get a standard replacement high pressure switch, and the appropriate connector, and wire it in series with the clutch.

This may not be the ideal solution if you don't need a compressor, but since my old compressor was a doorstop anyway, it's perfect for me.

Edit - Googled "Comfort Temp 6511358" and found nothing.
eBay, however, has Cadillac compressors with that same part number under the Global brand name, for under $200. Don't know if they're the same or not. I didn't find any pics of the rear head.



I have a new Delphi A/C compressor that I am looking at now and it has no provision to add the high pressure safety switch to the back. I will go with a simple make break switch located on a switch port aluminum brazed to the high side line and electrically placed in series with the clutch relay. I like the compressor switch solution better but an external high side safety switch will work. The way that the Fiero Factory was doing them was to just ignore the purpose of the safely switch and used only the cycle switch. Systems that were fully charged blew hoses and seals. Not a good way to do a swap A/C system.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

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Raydar
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Report this Post09-15-2014 09:18 PM Click Here to See the Profile for RaydarClick Here to Email RaydarSend a Private Message to RaydarEdit/Delete MessageReply w/QuoteDirect Link to This Post
That'll work.
I was pleasantly surprised that my compressor had the provisions for the switches but, obviously, that can't always be depended upon.
I feel good about my choice of compressor, however, as I asked them to sell me the same compressor that they would use if they were doing the job themselves.
I, and several of my friends, have dealt with them before. Always with good results. (Kell Radiator Service. Douglasville GA, for the locals.)

Good luck with yours.

[This message has been edited by Raydar (edited 09-15-2014).]

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Will
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Report this Post09-16-2014 05:14 PM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Raydar:

I found a solution to my situation.

I picked up my new compressor today. It's a Comfort Temp P/N 6511358. (Came from a local radiator and a/c repair shop.)
It's a new compressor, sold as a replacement for the Caddy 4.9. Price was $280. A good deal for a new compressor, compared to others that I've seen.
The "solution" is the fact that, instead of using a blank casting, it has dummy plugs in the rear compressor head, which can be removed and replaced with whatever switches you want to install.
I just plan to get a standard replacement high pressure switch, and the appropriate connector, and wire it in series with the clutch.

This may not be the ideal solution if you don't need a compressor, but since my old compressor was a doorstop anyway, it's perfect for me.

Edit - Googled "Comfort Temp 6511358" and found nothing.
eBay, however, has Cadillac compressors with that same part number under the Global brand name, for under $200. Don't know if they're the same or not. I didn't find any pics of the rear head.



 
quote
Originally posted by Dennis LaGrua:

I have a new Delphi A/C compressor that I am looking at now and it has no provision to add the high pressure safety switch to the back. I will go with a simple make break switch located on a switch port aluminum brazed to the high side line and electrically placed in series with the clutch relay. I like the compressor switch solution better but an external high side safety switch will work. The way that the Fiero Factory was doing them was to just ignore the purpose of the safely switch and used only the cycle switch. Systems that were fully charged blew hoses and seals. Not a good way to do a swap A/C system.



I'm in the same situation with my Northstar car.
I bought a new A/C Delco compressor for the Cadillac application and it did not have the locations to accept the Fiero-style safety switch machined at all... just a blind cored hole in the casting. Obviously the rear cap which would accept the switches could just bolt on, but that's opening up the little box of sorcery and witchcraft

I snagged a CarQuest A/C compressor catalog and have been biding for some time to rifle through it to see if there's a compressor on the market which has the correct front head clocked the correct direction, the correct rear head clocked the correct direction and the correct pulley...
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Raydar
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Report this Post09-17-2014 06:34 PM Click Here to See the Profile for RaydarClick Here to Email RaydarSend a Private Message to RaydarEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Will:
...
I bought a new A/C Delco compressor for the Cadillac application and it did not have the locations to accept the Fiero-style safety switch machined at all... just a blind cored hole in the casting.


I'm thinking that might be an economy measure with the Global brand, since they serve the aftermarket.
If they just had one rear head for the HR6, they could use it on all their compressors, and it would be suitable for most any application.
4.9 (and probably Northstar) Caddies would just leave the plugs in place, while the others could have the plugs removed and switches added.
Kind of "dumbs it down" for the assemblers, who won't have to match the correct head to the appropriate part number.
All speculation, of course.
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