Air Conditioning not working ?

[MarcStanley]

Went for a drive down the thruway today, first warm and sunny day of the year. Go to turn on the AC and no cold air comes. Air continued to blow out of the panel vents it just was not cold. The air was warm on both the pass side and driver side and both were the same temp, warm. When I stopped I looked and saw that the compressor wasn't running. I checked the ac fuse and relay and those weren't it. Also crawled under the truck and messed with the compressor connectors a little bit, not much, didn't do anything. I recently picked this truck up and when I test drove it a few weeks ago I checked the AC and it appeared to work (checked for cold air inside, not looking at the compressor). So do I have a leak, or is the compressor shot? Thanks guys in advance. 2003 QC SB 4x4, stock

 

[cycletech]

Try tapping on the a/c compressor clutch assembly and or disc while a/c is on and see if disc and clutch is stuck, sometimes when not in use for a while the coil distance is too great and wont magnetize and compressor wont work. just tap with hammer lightly on disc.

 

[SSwords]

Not to hijack the post but me to. I can cycle the ac and can hear the engine pull when I turn it on and off can you hear that because I do not see mine spin either? I hook gauges to mine and they both read 68psi high and low. I have never got in to ac work so I do not know if this is good or bad but they do not move when you cycle it on and off.

 

[TCDiesel]

If it's AT check the AT dip stick tube,it rubs against the AC line and puts a hole in it,it's very common.

 

[BHanna]

You've got several possibilities there. The compressor or clutch could be bad. You could have a leak. The low-pressure switch could be bad. I wouldn't assume it's a compressor problem. More likely it's something else.

SSwords, that pressure sounds about right but you really need to check it with the system running. Have you tried jumping across the low-pressure switch to see if that makes your compressor run?

 

[MarcStanley]

Thanks guys. I pulled off the lines at the compressor today and one of the o rings was shot. Does anyone know where to get these o rings? Will NAPA have them? Hopefully that is where the leak was now all i have to do is get someone to evacuate the system and then refill it.

 

[BHanna]

I would think NAPA would have them. What color was the o-ring? Was it deteriorated or damaged somehow? If it was deteriorated, you probably want to just pull everything apart while you have the system empty and replace all the o-rings. I think the green ones are what you want to put back in.

Does anyone know what the life expectancy of those o-rings are in a 3rd gen? I'd think it should be better than 7 yrs.

 

[MarcStanley]

here is what I pulled off from the back of the compressor. One of the o rings is worse then the other.

 

[BHanna]

That looks a little damaged. Hard to say if that was causing a leak though. I'd still lean toward taking all the hoses apart and replacing all the o-rings/seals. It's cheap and doesn't take that much time.

It also wouldn't be a bad idea to flush your condenser & evaporator, replace the drier and put new oil in it before you seal it back up. Then you could be pretty sure it'll seal and last at least 7 or 8 more years.

 

[SSwords]

Ok I got finaly got a brake to where I can play agian. I pulled the conector off the low pressure switch and it has 3 wires on it what do I need to jump across to find if it is bad. Also can I just make a toggle switch on it until I get the new ac machine at work ? ( I know I am cheep)

 

[rbattelle]

Also can I just make a toggle switch on it until I get the new ac machine at work ? ( I know I am cheep)

How will you know when to shut off the compressor?



Ryan

 

[SSwords]

That's a good point! Like I said the mechanical side of me stops before AC work. But is their a way to jump across to see if my ac works for a few minuets ?

 

[rbattelle]

Well, if I'm reading the wiring diagram correctly, there should be 2 wires going to the A/C compressor clutch. One is dark blue with a black stripe, and the other is black with a brown stripe.

You can do one of two things. Either,

1) Ground the dark blue / black stripe wire, or
2) Jump the dark blue /black stripe wire to the black / brown stripe wire.

These two wires are in the A/C clutch connector. In fact, they're the only 2 wires in that connector.

Ryan

 

[ttbird]

He was asking which of the three wires at the connector for the low pressure switch he needs to jumper to get the clutch to engage. My second gen only has two wires there so it's a no brainer for me which ones to jumper. Jumpering at the low pressure switch will turn on the clutch, even if it's low on charge. Compressor should be running when adding anything to the system. If pressure is correct and compressor running when you jumper the switch then the low pressure switch needs replaced. It can be replaced with the system charged.

 

[rbattelle]

He was asking which of the three wires at the connector for the low pressure switch he needs to jumper to get the clutch to engage.

I know, but I figured it's easier to just jump the clutch itself. However, my advice was no good anyway because I don't think grounding or jumping those wires will work.



To make my suggestion actually work to actuate the clutch, you'd want to apply +12v to the dark blue wire with the black stripe on the compressor clutch side of the circuit!



As for the pressure switch, sensor ground is light blue with a white stripe, +5v supply is dark green with an orange stripe, and the pressure signal itself is dark blue with no stripe. I don't think that jumping any of these wires will cause the clutch to engage. The ECM determines clutch engagement based on the pressure signal.



Have you checked whether the system has any pressure?



Ryan

 

[SSwords]

Ok I got to play with this the other day and I can get the clutch to engage by jumping at the clutch but can not by jumping at the low press switch. The PCM is working because when I hit the ac button in the dash my idle will raise from 800 to 820 according to my TST and you can here it. I got a new toy at the shop and had to give a class on it so I sucked down and refilled my truck so I know it has the right amount of freon. I am not getting any codes for the ac from reading with the key method at the dash. I am not having trouble with the truck over heating but could it be the fan clutch and do I have to suck the system down to take out the low pressure switch because if not I will swap them from my truck to my dads then I will know if that is it. I just relay hate throwing money at a problem with out knowing that it will fix it.