I have an 86 2m4 in the shop for AC, they converted it to R134, but said it is not blowing quite as cold as they would like. They said the line that returns to the compressor from the front of the car has a spot that is slightly crushed and they are trying to decide if that could be the reason it doesn’t cool as well as it could. The guy is going to add a little more fluid and see if that does the trick.

*Anyone here know, would an alteration such as a slight crush in the line that returns to the compressor (lower pressure line) somehow reduce the cooling ability? I asked if it could restrict it and cause the compressor to work harder, and they said no, the orifice tube restricts it much more.

They said it is too tight to splice in some line with connectors, and as far as they know, there is no source for new line. Not to mention $pendy for that.
thanks

If the return line has a slight dent in it, but it is still outflowing the restriction at the compressor inlet, then it's probably unrelated. It could just be that the length of the lines in the Fiero mean it is slightly less efficient, and so it is not getting as cold as they are used to, but it's probably "close enough" to work. R134-A also won't be as cold as R-12 was originally in the car. So those two factors are probably the big things playing into their temp readings being close but not what they are used to seeing.

There could be an actual problem somewhere two, but it sounds like it's working good, and they are just used to having the air blow colder, with cars where the AC lines are much shorter since they're right next to the firewall. Is it the Fiero compressor, or did they install a new compressor designed for R134?

Its the Fiero compressor.

How old is your compressor? Keep in mind that the Fiero's condenser is sized for R-12 and won't cool as effectively with R-134a. Since the Fiero's cabin is so small, even a less efficient system running R-134a cools pretty well.

I doubt the restriction is having any effect on cooling performance. Did the guy say what the vent temperature is?

The Fiero FSM says that with the a/c on max, the vent outlet temperature should be approximately 40 degrees F. FWIW, the vent temperature is not 40 F on my vehicle and my compressor is new.

Stock compressor with R-134a, then I definitely stick with what I said before. The long lines on the Fiero, and the simply less efficient cooling due to using R-134a in a compressor designed for R12. With the small cabin it should still get cold quick, and they are probably trying to get around 36-38F out of the vent, while it's probably giving about 43 or so, from a rough guess based on what you said.

If the vent temp is low 40s, I'd tell them to pack it up and be done with it, you won't really get any better than that on a used stock compressor pumping R-134a.

On the 2.5 engines that used the V5 compressor, there is a compressor control valve that is made for the R12 refrigreant. There is a replacement control valve for R134A. If you do not put it in , it will never ccool correctly. V5 compressor only. About $85.00

[This message has been edited by josef644 (edited 06-16-2011).]

quote Originally posted by 2.5: The guy is going to add a little more fluid and see if that does the trick.

He doesn't know whether or not he used the correct amount of R-134a in the first place? This does not inspire confidence. "A little more" could make things worse, rather than better.

[This message has been edited by Marvin McInnis (edited 06-18-2011).]

quote Originally posted by masospaghetti: How old is your compressor? Keep in mind that the Fiero's condenser is sized for R-12 and won't cool as effectively with R-134a. Since the Fiero's cabin is so small, even a less efficient system running R-134a cools pretty well. I doubt the restriction is having any effect on cooling performance. Did the guy say what the vent temperature is? The Fiero FSM says that with the a/c on max, the vent outlet temperature should be approximately 40 degrees F. FWIW, the vent temperature is not 40 F on my vehicle and my compressor is new.

He actualy said they were shooting for 30's vent temp, it is currently 40.
Maybe thats what we get. Its the original compressor.
thanks all

quote Originally posted by 2.5: I'd love to know more about this, where can I get one? Maybe they did not know this, can it be easily replaced?

Me too! I am about to convert my Duke to R134a shortly. I need to know if i should change something out first.

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86 Fiero 2M4 Silver, and 86 GT

quote Originally posted by 2.5: He actualy said they were shooting for 30's vent temp, it is currently 40. Maybe thats what we get. Its the original compressor. thanks all

If you are getting 40F then consider yourself lucky. That is awesome for a 20+ something year old car. I guess they are used to working on new cars if they are expecting 30s .

40* is pretty good - the R134 control valve for the compressor will make a difference - they are available through most parts stores. It will require an evac of the system - fairly easy to remove/install.

I don't know but does the 86 4cyl use the v5? Just make sure before buying parts...

Charlie

quote Originally posted by cptsnoopy: I don't know but does the 86 4cyl use the v5? Just make sure before buying parts... Charlie

86 Duke used a V belt V5, 87-88 Dukes used a serpentine belted V5

I purchased my last compressor control valve at NAPA, but I have seen them at other sellers also. If you are having 40* coming out leave it alone.

[This message has been edited by josef644 (edited 06-17-2011).]

We've done a few R-134 conversions and all have blown very cold air. My own R-134 system that uses the Grand Prix compressor and GTP PCM control is ice cold even on 90*F+ days. My other system that uses the Fiero OEM control scheme also runs cold. If you have sound working components, a new orifice tube and accumulator,have done the charging process correctly, the system should run great on R-134a.
Possible causes of poor cooling.
1. Clogged condenser. (clean all of the bugs and debris from it) BTW this is a very common and simple fix. if air isn't getting to the condenser, low colling efficiency results.
2. Excessive amount of refrigerent oil (more oil = less refrigerent)
3. Dirt from a blown compressor, clogging the system and condenser. If the compressor blows, flushing the lines and condneser is necessary.
4. Worn compressor. They do wear out. One in use for 25 years won't give optimum performance
5 Moisture or air in the system
6. A low R-134a charge.
High side readings must be approx 2 times the outside temperature + 20%
at 90* F this means a high side reading of 208-210 PSI
Low side readings about 25 PSI

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's 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 "

1. You have V5 compressor? Did they change Control Valve? No? Then all above won't matter.

V5 needs correct control. One for R12. Another for R134a.
Using R12 control w/ R134 will work but system will not get good performance. Fiero's AC system is overbuild for such a small space....

If "shop" doesn't know then...... Find a real AC shop.

2. "The guy is going to add a little more fluid and see if that does the trick."

If "shop" doesn't know how much R134 then...... Uses no scale or using small cans....
Find a real AC shop.

3. 40* output air temp at center vent? How hot is the shop? Spec are 40* lower then intake air... If shop and car is 90* then output air reads 40* then different is 50*... Mean AC is likely fine.

Find a real AC shop.

See my cave, hvac section.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

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