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Evac the system and dried it out with my A/C tool kit and fan
I checked for power to Anti-Freeze Protection switch and the Low Pressure switch. No power with Test Light
Checked fuses 8 (A/C), 13 (Supplemental A/C) and 29 (A/C Condenser Fan). Replaced 29, it was blown.
AC Switch in the dash lights up and the blower on front and rear both work
Still no Compressor. I ordered a Relay XVIII according to the 928 Specialist chart 1986 attached. Went to the 5th position from the right on the top row of the relays and it is not XVIII. Went to the one on each side and it was not XVIII. I did not see XVIII on any of the relays, will check again, can't imagine I have a relay that is XX without having relay XVIII.. Am I missing something? Is the 1986 and 1986 1/2 different electrical panel? Thought the only difference between the 2 versions was 2 piston ABS (and one other thing that doesn't come to mind.
NOTE you may need a coolant change for your eye sight system,
so it can cope with the higher operating temperatures.
I suggest HOAF- RQ 615, this is the best eye coolant available,
it comes in individual and bulk sizes .
NOTE use a bright flashlight I suggest the Streamlight.
Boaf,
I think you may be misunderstanding. If you’re not getting voltage at the input to the freeze switch with AC turned on, then the failed AC relay everyone is talking about is not on the central electric panel - it’s in the HVAC control head unit. Other known problem areas include bad contacts at the HVAC board with the large slide-on connectors and faulty wiring between the HVAC head and the freeze switch.
Here is some generalized advice, with the caveat that I'm not an expert in the 86.5 in particular. I’d start by ensuring your fuses are all ok, not blown and seated well/not oxidized. Then re-verify voltage (or lack thereof) at the freeze switch with AC engaged. With a voltmeter. Between the input and any ground. If it’s low or absent, next stop is to pull out the HVAC control head. Have DeOxit ready so you can clean the connections while it’s out.
It’s also a good idea to get a copy of the wiring diagram for your car and understand how the AC circuit works.
Please read through these links. They will help you debug the problem.
PS note that if your AC system is still evacuated (you didn’t state if it was refilled), then the AC compressor will be prevented from engaging by the low pressure switch anyway.
Boaf, the relay we're referring to is at the upper left.
Kevin -- one minor detail, the '83 (and in fact 80-83 as far as I can tell) does not have the infamous relay. That started in 1984 cars. With 80-83, a relay is mounted in that location on the board, but it's a different type of relay and for a completely different purpose. The AC +12V power goes right through the copper trace on the HVAC "slider" directly with no relay involved there at all. Which is even worse, because if there's a high current condition, the copper traces could be destroyed! I installed a relay at the CE panel to take the load in my '83 (triggered by the HVAC) for that reason. For anyone who wants to go down THAT rabbit hole: https://rennlist.com/forums/928-foru...o-78-84-a.html
Boaf, the relay we're referring to is at the upper left.
Kevin -- one minor detail, the '83 (and in fact 80-83 as far as I can tell) does not have the infamous relay. That started in 1984 cars. With 80-83, a relay is mounted in that location on the board, but it's a different type of relay and for a completely different purpose. The AC +12V power goes right through the copper trace on the HVAC "slider" directly with no relay involved there at all. Which is even worse, because if there's a high current condition, the copper traces could be destroyed! I installed a relay at the CE panel to take the load in my '83 (triggered by the HVAC) for that reason. For anyone who wants to go down THAT rabbit hole: https://rennlist.com/forums/928-foru...o-78-84-a.html
Update: I found and replaced XVIII relay, see below.
RJTW,
Thanks so much for the guide, I appreciate it and for the links. I will review today. I responded in bold with some questions.
Originally Posted by rjtw
Boaf,
I think you may be misunderstanding. If you’re not getting voltage at the input to the freeze switch with AC turned on, then the failed AC relay everyone is talking about is not on the central electric panel - it’s in the HVAC control head unit. OK, I understand, will look at the A/C head control unit. Wasn't sure what it was. I do get the light that the A/C is on, and blower motor. I did finally locate the relay in the electrical panel, see the attached relay.
Other known problem areas include bad contacts at the HVAC board with the large slide-on connectors and faulty wiring between the HVAC head and the freeze switch.
Here is some generalized advice, with the caveat that I'm not an expert in the 86.5 in particular. I’d start by ensuring your fuses are all ok, not blown and seated well/not oxidized Confirmed, I looked at the 3 fuses 8, 13 and 29 (replaced all of them for good measure).. Then re-verify voltage (or lack thereof) at the freeze switch with AC engaged A/C engaged, I used my test light. Will check again with volt meter, but not feeling positive.. With a voltmeter. Between the input and any ground. If it’s low or absent, next stop is to pull out the HVAC control head Same question, . Have DeOxit ready so you can clean the connections while it’s out. I do and will
It’s also a good idea to get a copy of the wiring diagram for your car and understand how the AC circuit works. Will look in my folder, I have had the car for almost 20 years, should have it
Please read through these links. They will help you debug the problem.
PS note that if your AC system is still evacuated (you didn’t state if it was refilled), then the AC compressor will be prevented from engaging by the low pressure switch anyway. It is pressurized.
08-22-2024, 10:28 AM
1986 1/2 A/C Relay
