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Testing A/C Compressor

22K views 16 replies 10 participants last post by  XT2015 
#1 ·
Yes, another A/C question... For the last year or two my A/C has not worked on my 2002. Since I only drive it once in awhile I kept pushing it off, but it is finally time to fix it.

Initially I thought it was an electrical problem, but it turned out my multimeter was bad. I discovered this afternoon that the high pressure hose has a gash in it and it appears it somehow hit the flywheel on the front of the compressor and sliced it open. See attached pics.

I got voltage at both fuses in the panel under the hood and at the dryer. How do I confirm the compressor is still good and didn't get toasted when the high pressure line blew? I'm assuming the low pressure switch on the dryer turned the compressor off before this happened, but I want to confirm before I order a new hose and dryer. I also put a guage on the low pressure port and it was at zero (not suprising).

If the compressor is still good, I replace the high pressure line and dryer, run an A/C vac then recharge the system right?

Thanks in advance for the help.
 

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#2 ·
Open your hood, start your truck. Turn on the AC on high and put it on defrost. Watch for compressor clutch to kick in.
 
#3 ·
I tried that and the compressor did not kick on, but I don't see how that is any different then turning the A/C on high. Since there is a low pressure switch, wouldn't that keep the compressor from turning on if all the freon escaped? I guess I'm just trying to figure out a way to confirm that the compressor works before I order the high pressure hose and dryer... Any ideas?
 
#4 ·
No, it should turn on. You can always put an amp clamp around the trigger wire.
 
#5 ·
You can always jumper the connector on the low pressure switch to test the comp. I'm pretty sure James is right about defrost though. There's an AC switch that closes when you go to defrost, but with out getting out the schematics, I'm not certain it will bypass the low pressure switch.
 
#6 ·
Jump the switch on the drier if u don' have freon in its the only thing that will engage the clutch
 
#7 ·
so if you jump the low pressure switch connector the compressor should engage? did that today and it was a nogo. i cant do the defrost setting due to the fact that i have disengaged the micro switch behind the knob.
 
#8 ·
Bring this one back from the dead... I didn't get around to fixing the A/C last year, but I need to get it running ASAP...

I spent some time last night reading thru the repair manual and attempting to troubleshoot the system. Here is what I found:

- I could not get the clutch to engage when I jumped the wiring running to the dryer.
- I ran a wire from the battery to the compressor and the clutch engages.
- I checked the A/C fuses under the hood and they are in good shape. I also used a multimeter to confirm both fuses are getting power.
- The power lead running to the compressor is not getting any power.

Any idea where to power lead running to the compressor originates? I tried to track it down, but it joins a large bundle of wires and goes thru the center of the firewall.

Any other things I should check?
 
#10 ·
I know the system is empty because I have not replaced the high pressure hose yet.

If I jump the dryer and still not getting power to the compressor lead, any idea what I should check next?

What about if I'm not getting power to the dryer?

I looked at the wiring diagram, but could not make sense of it.
 
#11 ·
Something to keep in mind before you go spend several hundred dollars to have a repair garage evacuate and refill your A/C system; for less than 200 dollars, you can purchse a complete A/C vacume pump and manifold system from Amazon, and you'll have it for future use.
 
#12 ·
I agree on the A/C gauge and pump, thats the route I'm heading.

I burned some more time last night going thru the system and it appears the power isn't getting any further then the dash mounted climate control unit. I don't have any power at the compressor, dryer or thermal control amp.

I believe last year when I was messing around with the A/C, I jumped the wrong wires on the thermal control amp and after that the A/C light and the defrost light no longer worked on the climate control unit. I'm pretty sure I fried something on the board. With that being said, I tried to remove it last night, but I can't get the two cables that control the air flow to disconnect from the unit. I also went thru the service manual, but wasn't able to find anything.

Any ideas???
 
#13 ·
let me just throw this at you.... my 00 did the same thing. my system was full, light was lit on the dash, but compressor would not start. turns out the dash switch was bad.....hooked it up on a toggle switch and it has worked fine since. as i did see in a previous reply though... you do have to make sure the system is fully charged or it will not start
 
#14 ·
Well I got the climate control assembly out and ordered a new one off of Courtesy Parts, but I just got word that the part is on indefinite back order. I was able to find a climate control assembly for an XE model, but no one can give me an answer if it will fit in a SE-SC model.

Does anyone know if the climate control assembly for a 2002 XE will fit in a 2002 SE-SC????
 
#16 ·
@idjikaity
That post is 10 years old so you might not get a reply.

I've found the FSMs to be helpful and I'm sure they will continue to do so. Here's a link to download them for free.

 
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#17 ·
@idjikaity
That post is 10 years old so you might not get a reply.

I've found the FSMs to be helpful and I'm sure they will continue to do so. Here's a link to download them for free.

Additional note: Page 27 in FSM....component location.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
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