A/C questions..

[GMCYukalade]

Ok, so.. i have a 99 Yukon with rear-air - My front air is warm.. - i have cleaned the Evap core - still warm - charged the system - still warm - now, i went to check it, and it was back down to 15psi (after 3 weeks of leaving it alone) so i know it has a slow leak - - but that isn't all - i have a question about why it isn't cold - i know even if it has 35psi in it, it should be cold - right now it is at 45 (max) - now, the Compressor will kick on, and then run for a couple seconds and go off - i don't know if this is normal - there is a sensor on it - do you think that sensor is failing? - also - the sensor on the thing near the cab.. what is it for? - i don't know i guess i'm askin what all i need to trouble-shoot for the air

- Edit -
Also, when i pulled the blower motor out, there is a metal clip on one of the fins, that looks kinda like a staple, but it was bent and put on there.. i think - is that factory? like a balance or something?

 

[Sidescrollin]

well to begin with , when you put 45psi of freon and check to see if its cold are you starting the engine. Thats really important when youre checking because if your jsut turning the electrical on its not gonna be cold. Also you should be able to here it run for a bit mines like 5 min and then itll go off.

 

[GMCYukalade]

When i fill the system with freeon - the motor is running, with both rear and front air turned on high w/ a/c on..

 

[Sidescrollin]

hmm well i honestly dont kow **** about a/cs but i dont think the Compressor should be shutting off as quickly as your saying. to add to what you siad , youve been adding freon since its leaking , if its overcharged that could cause the compressor to shut off. and mind you if its not overcharged but at max and then it gets hot thatll build the pressure over and the compressor might not work.
The a/c sensor could be busted and that could be making your compressor short cycle.

 

[GMCYukalade]

Is that the sensor on the compressor? - i have a 97 yukon setting in the drive as well - so i can always borrow a sensor.. - that is, unless the sensor is a pressure sensor.. because the 97s ac works great, and i dont want to go and release freeon everywhere

 

[Sidescrollin]

yes the sensor im talking about is a pressure sensor...i wouldnt bother with the 97 cuz then u have a mess and need to buy more freon

 

[Budreau68]

The pressure switches should have a shrader valve (think tires) behind it. A little refridgerant might leak out when you take it off but should shut off. There are two pressure switches on my 95. The one on the compressor is the high side switch. Evaporator is the low side switch.

 

[GMCYukalade]

Well, i think i found my main problem - my compressor isn't running, unless i am charging it.. - so i belive it is the sensor on the compressor.. - However it isn't holding pressure either (it leaks down REALLY slow like in 2 weeks it will need some more juice put in to it) - but i don't know if that is the orifice tube or not.. i havent found any leaks

 

[Budreau68]

Unless there is enough pressure in the line the compressor should not run. The only way to get the compressor to run with little to no pressure is by jumping the pressure switch(es) that are currently off due to low pressure. However, running the compressor in such a way for very long will damage the compressor.

As for the leak, they can be nearly impossible to find, especially if they are slow. Some refridgerants have dye and a UV light to find the leaks. Good luck. Especially if the leak is on the Evaporator (radiator inside the dash).

I had said earlier there are two pressure switches one on the compressor, one on the evaporator. I meant to say the second switch is on the acumulator not the evaporator, sorry.

 

[GMCYukalade]

You dont understand what i'm sayin - when my pressure is at 35-45 psi then my compressor will not kick on, unless i am actually charging the system IE: forcing more freeon in the system as soon as i stop a few mins later compressor will just stop running and will not kick back on

 

[Budreau68]

You're right

I didn't understand it that way. Sounds like a pretty big problem, you should probably take it in. My only other thoughts would be to ensure you're filling the low side versus the high side. And you could start replacing the pressure switches, at about $20 a pop times 2, that could be a $40 investment on a system that still leaks freon.

 

[GMCYukalade]

- well, i'm charging the side with the really big tube (the only side the charge bottle will click on-to) the other side the fitting is too big to hook onto with my a/c guage

 

[Rollin Thunder]

for 200 throw a new one in and enjoy the coldest ac ever. Just put a new one in the mustang and 380sl COLDEST EVER, mustang Gt is colder than the yukon at 60. 200 bucks (to me) is not all that much for what you get out of it. Plus you usually get a new warrenty plus they will last for a long time, and you have cold ac again. You sound very mechnically inclined, so im sure you can install it.

http://www.autopartswarehouse.com/d...coQQA-fs-C_CompressorQQ19961999QQMP34515.html

 

[kinggreen803]

Yo Believe It Or Not But When I First Got To Kansas From Germany My Ac In My Vehicle Went Out. I Tried Recharging And Everything. I Even Took It To Shop And The Damn Mechanics There Couldnt Figure It Out. So I Took It Home After Paying For Freon And All Kinds Of ****. Guess What My Wife Said Check The Antifreeze, I Couldnt Believe It But After I Added Antifreeze My Damn Ac Started To Work. Just A Suggestion It Might Work It Might Not It Is Worth Trying.......................

 

[sasquatch094]

I just jumped to the bottom of the thread not reading alot, but maybe u should buy a GM seal kit for the compressor. But then it wouldnt make sense as to why its not running... Im in the process of taking mine apart and have parts coming in tomorrow (gaskets and seals) then im putting it all back together.... A new compressor is like 350 bucks or something from GM.. the seal kit and everything was like 20.. worth a try.... Do u know where its leaking from? get a sniffer and chase that SOB.. i had a huge leak off the compressor thats why i did all this, and i changed the clutch..

 

[Budreau68]

Big tube is the low side, so that's correct. And I forgot the fill bottle shouldn't even fit on the high side.

I like the idea about the Anti-freeze. Still, if you can't find the freon leak, it doesn't matter why the compressor doesn't run.

Maybe the tubes are clogged somewhere. So you're getting an over pressure shutoff after a few minutes of use. A clog would allow the compressor to run, building pressure, the AC would never get cold as the system is not flowing. After a few minutes the pressure would be great enough, I think there's an over pressure kill switch.

Have you changed the filter/drier?

Was the system empty/unpressurized? That would allow moisture into the system and clog the drier.

 

[GMCYukalade]

Where is this filter/drier at? - as a side note, my rear a/c works great when the compressor is running

 

[sasquatch094]

Just fixed my leak on the compressor today and my dad charged the AC.. within 2 min of running time it got 40 degrees inside my truck, the windows were frosted and all the lines in the engine compartment were frosted.. it was like 75 before i had the AC on..

 

[JP422]

Sasquatch... do you have any more info or tips on this AC compressor seal kit? Was it difficult? any special tools needed? My AC was down for a few yrs, and I thought it was due to a leak in the pipes... anyway I changed all the pipes and O-rings, filter and drier canister... and took it in for a vacuum and fill. It was ok for a week, but the mechanic told me the most common problem is the 3 piece AC compressor housing. He said it will leak eventually... especially at my Denali's age and mileage (1999 w/ 160k+ miles).

Sure enough, there today I saw the small leak and bubbles... as well as dye stain all under the compressor housing. What a pisser. Now it's either rebuild or replace.
I am mechanically inclined... but just don't want to throw too much $$$ at the Yukon right now.

So what's better... an aftermarket AC compressor... or rebuilt GM one?

Thanks for your tips!~

 

[sasquatch094]

umm i called up GM partstore right over the phone and ordered everything, i could dig up the receipts if you want them for the part numbers, but 99 and 95 may be different. but it wasnt too hard to take apart, be very careful in doing so tho..