kaelix

Alternator belt broke and took out the fan harness, ps belt, and AC connection (black wire from main harness -> red wire from compressor), AC compressor belt did not break.

I finally got a new alternator and both belts (alt and ps) replaced, and created a new harness for both fans.

I started the car for the first time since this happened. Both fans work with A/C button pressed () and everything seems to be running fine.

BUT my AC used to blow ice cold (could freeze your arm off) but now it's not working.

The clutch (black piece in the center right?) doesn't seem to be engaging (not spinning). I disconnected the leads I rebuilt, thinking maybe i messed those up. I had some extra wire and connectors so I rigged up some pieces to be able to test from up top.

No fuses were blown, they're all fine.

With the car running at idle i get around 13.02V from ground -> meter -> + jump post

From black wire -> meter -> red compressor wire i get 12.26V (so my connections must be ok right?)

From red compressor wire -> meter -> compressor body I get about 3.5 ohms

That's as far as i got, i don't know what else to test. I could use some help, it's a hot Texas summer after all....

Ducman82

That black wire to the compressor should be 12v from switch. Sounds like bad connection

kaelix

Going to have to noob it down for me, I thought black wire -> meter -> red compressor wire i get 12.26V was good, you're saying it should be 12V? How/where else should I test this? Oh also forgot to mention i went from + jump post -> meter -> red compressor wire, still nothing.

Ducman82

hummm... test to see if you are getting 12v from that wire from the harness.

kaelix

I redid the connectors just to be on the safe side.

With the car running, the tester to the jumper of the black wire I get only mv readings, so looks like no 12V

If i jump from the red compressor wire to the + jump post, the clutch kicks in, so at least now i know it's working.

What do i have to do next to troubleshoot why i'm not getting 12V to the black wire in the harness

Ducman82

check the 14 pin connector. see if the pin for that black wire is getting juice there. if it is, then the harness repair was no good.

Alan

Check the refrigerant pressure switch on the dryer - pull the connections off & test the switch itself - if its not conducting you have likely lost refrigerant.

Using a meter (DMM) in volts mode only connect the ground (black probe) to an actual ground NOT anything else - you will just confuse yourself (and likely everyone else too).

Alan

kaelix

Ok new day, started over to simplify things and not confuse myself. I created a jumper from ground point MPII to make sure I got a good ground, and the black lead from the volt meter is connected to this jumper.

With the car running (and touching the red lead to the following):
@jump post = 13.2V
@ black wire from harness = 13.2V
@ pin 9 = 13.2V

So it looks like I am getting at least 12V to the black wire, however when I connect it to the red wire, still no clutch

red wire -> jump post = spark and clutch engages.

How do i pull the connections off & test the switch itself?

In reading other AC threads I found this:
"The circuit is simple: headunit relay ---> freeze switch ---> low pressure switch --->pin 9 of 14-pin connector ---> compressor clutch wire"

So if i'm getting 13.2 at pin 9 and the black wire wouldn't it mean the low pressure switch is functioning correctly?

Alan

Is the compressor clutch grounded correctly to the compressor body?

Are you testing pin 9 voltage with the clutch attached? if not test it in circuit while running - you may get different results than when unloaded.

Alan

kaelix

How would I test this? When i touch the red compressor wire to the + jump post, the clutch engages, does that mean it's correctly grounded?

If i understand this correctly I was testing it unloaded. I connected the black wire and the red compressor wire, then touched the red test lead to pin 9 = .9V

Alan

You should just be able to see the clutch grounding wire to the compressor body - but your test also confirms it's OK of course - so it isn't that.

OK this is the classic symptom of a failed AC relay in the head unit. It connects but there is high resistance in the connection - with no load at all you see 12+ volts but with any realistic current loading you see almost nothing.

See many previous threads on this topic

Alan

kaelix

Looks like Dwayne has a write up on this procedure. Thanks, once again, Alan and Duckman for helping me out.