86 GT High Idle and A/C Shennanigans... Related? (Page 2/2)
Time Traveller JUN 19, 12:18 AM
I did some testing based on what I've found online and in the service manual regarding the blower issue, and it seems like my resistors are too resistant (~8-10 ohm, should be <1, right?), and it seems I need to check the blower motor High Speed Relay. I got 12.4v across the motor with the car off and fan switch in hi, and 11.7 or so in the other settings, with the motor not running. I did not do this with a test load as Ogre's Cave recommends, but are these values too far apart to the point of indicating a shot blower?

That said, if the blower worked in HI with the A/C running, it'd be fine, but it cuts out in any compressor modes. The SM says to conduct the High Speed Relay test in vent mode, somewhat prescient given my circumstances. I'll probably also get in there and clean any fuzz out of the evap this weekend.

DEFINITELY open to any other suggestions on the A/C thing. We topped 97 here today
Time Traveller JUN 21, 12:11 PM
So, presuming the idle issue IS separate and behaving normally, the A/C blower cutting out on any speed other than HI, and cutting out on HI when the A/C is engaged, remains.
I've conducted all the tests on the blower motor system as outlined in the service manual.
-After some cleaning, the blower resistors are all around 1 ohm when back-probed.
-The A/C Power relay and High Speed Relay seem to function properly.
-Speed switch has continuity per each setting.
-Voltage across the motor is 11.86 on vent/HI with the motor connected or disconnected, and the engine not running. HOWEVER, if the disconnected voltage drops at all (~11.7-11.6 on resistors, 11.42 when AC engaged), the motor seemingly shorts the circuit when connected (dropping the voltage across the motor to like 0.15). I took the motor out and cleaned out a bunch of the carbon with electronics cleaner, let dry overnight, and tried again, same result.

Do I assume correctly that this means the motor is shot? Or am I missing something, and a different component is the cause? Is the voltage drop across the resistors or AC system abnormally high, indicating a different problem?
Time Traveller JUN 23, 01:53 PM
Tried a new Four Seasons blower motor, symptoms still the same. The armature on the old motor spins about as easily as the brand new one. When I get home I'll do voltage and current tests across both motors, but I feel like I'm missing the real issue. The resistors in these cars don't look like they could have an integrated fuse, which seems to be a common complaint with the newer style resistors, and my motor wire voltage doesn't cut out completely when the resistors are engaged, only when the old motor was connected. The resistances aren't perfect to the factory spec of .5 and .7 ohms or whatever, but I think I read a post somewhere here suggesting that cheap multi-meters aren't going to get an accurate reading on that small of a resistance anyway. Is there a way to be sure on these? I've noticed they're not really an obtainable item.

EDIT:
I was monkeying around with some final tests to both the new and old motors, when it briefly shuddered to life in the low fan setting. One thing I hadn't done yet was swap the A/C Power and High Speed Relays.... Turns out, the relay was shot. A new relay set everything right. I'm not sure how the relay passed the testing I did per the shop manual, but that's that.
Also of note: Since the ECM hasn't experienced the compressor running since the last reset, the idle dropped way off when I first engaged the compressor. A short jaunt with A/C running fixed that. I guess one should use the A/C, if equipped, during the idle re-learning drive.

[This message has been edited by Time Traveller (edited 06-23-2020).]