Ac wiring for 88 2.5 (Page 1/1)
handymanpat MAY 14, 10:20 PM
I have an 88 tech 4 engine and I cannot get the ac to kick on.
There is no low pressure switch up front on the accumulator but there are two round pressure switches located on the ac compressor itself.
I have vacuumed the system and filled it with coolant but it won't trip on until I jumper it at the plug where it connects to the ac relay (the one next to the fuel pump relay behind the driver seat)
I have swapped the two relays and the car starts and runs so the relay is good.
I have also not been able to kick on the radiator fan when I push the max ac. I have swapped out that climate control unit with two others and it made no difference so I will need to deal with that also.
The fuses under the dash are all good.
I have read that the 88 tech 4 engine has the ac and the radiator fan run by the ecm. There is no actual sensor that kicks on the radiator fan like the other 2.5 engines, the computer does it?
Does anyone have any advice as to why the radiator and ac will not kick on? Is this all run through the ecm? If so could the ecm be fine except for the ac and radiator fan function?
That does not seem to make sense.
I really hate this engine and wiring!
If I were to jumper the ac at the relay will the ac shut off if it gets over pressured? Or under pressured?
If so, couldn't I just run the compressor that way and let the pressure switches trip off the compressor if and when it needed to?
Or will the compressor just keep running and cause a problem?
Thanks for any advice.
Pat

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pat moody

theogre MAY 15, 07:19 PM
87-88 Duke has V5 compressor and not = to others including wiring. V5 (and V7) are not "clutch slapper" to regulate system pressure. That job is valve in the compressor.

Like many, Is a low pressure switch on the compressor. But No Clutch switch on Accum/Drier as other Fiero and more.

Rad Fan is function of control head and On in Max and normal AC.

ECM "watches" all switches and final say the compressors runs. Is so when you "floor the gas" the compressor shuts Off.
ECM reports AC in the data stream. You need AC Demand = On/True when all AC switches close and engine runs.

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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)

The Ogre's Fiero Cave

handymanpat MAY 16, 07:03 AM

Hello!
I appreciate your posting a response.
I had spent quite a bit more time trying to search as to why neither one would work. I even took a radiator fan plug tip and section of wire from an old harness and ran that up to the fuse box and wired it in so the fan would come on with the key turned so I would not overheat the car.
I was out there trying to mess with the wiring to the compressor, testing it to try and get it figured out.
I had vacuumed and filled the coolant system and was going to try and jumper the plug tip to the ac from the relay.
Lucky for me the car was running and the max ac was on at the time.
I started working at getting the plug pulled out of the relay and as I was wiggling and pulling it I heard the compressor kick in and the engine bog down!
I pushed the plug back into the relay and it shutoff!
I pulled it a little way back again and it kicked in again!!
Holy cow, that plug tip was not making good contact with the relay!
I just read your message now and wanted to let you know.
I bet now when I go out and plug in the original radiator fan plug back in that it will turn the fan on when the max ac is on.
I will know for sure in a couple hours when I go back out.
It was pouring rain last night and only the back half of the car was in the garage.
I will post my finding to you.
Thank you for taking the time to help out with this stuff, we all appreciate it.
Thanks again.
Pat

quote
Originally posted by theogre:

87-88 Duke has V5 compressor and not = to others including wiring. V5 (and V7) are not "clutch slapper" to regulate system pressure. That job is valve in the compressor.

Like many, Is a low pressure switch on the compressor. But No Clutch switch on Accum/Drier as other Fiero and more.

Rad Fan is function of control head and On in Max and normal AC.

ECM "watches" all switches and final say the compressors runs. Is so when you "floor the gas" the compressor shuts Off.
ECM reports AC in the data stream. You need AC Demand = On/True when all AC switches close and engine runs.




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pat moody