Help! My ac is not working..

nc37 · 06-25-2009, 05:41 PM

My AC stopped working this morning. Thinking it may be low on charge, I stopped by autozone and picked up a can of 134A along with a gauge.

The AC compressor is not kicking on. Thus, I can not add 134A since it can not flow into the system and just builds pressure on the connection.

The presssure on the low side appears to be reading les than 28 PSIG.

Question is: How can I make the compressor start and allow the refrigerant to be pulled into the system?

Thanks

**octaneman** · 06-25-2009, 09:11 PM

Hi nc37

First thing you need to know if the compressor has not seized up. Check to see if the A/C belt is still on or slipping. In order to add the freon the system has to be evacuated and then checked for leaks. The only way to do that is with an A/C machine, once evacuated and no leaks appear, the compressor oil is added then the freon at 2.2 lbs. Check the fuse box for blown fuse, also look at the A/C controller to verify if power goes to it ,jump the pins on the controller to see if the compressor activates.

**Raylo** · 06-26-2009, 07:38 AM

It is usually possible to charge a system w/o the comp running and get enough charge in to make the LP switch shut and start cycling the comp. There are some ways to help this along. You can also bypass the LP switch to make the comp cycle on early for charging. But from what we know here I would definitely not recommend it.

Based on the r134a pressure/temp chart (see link below) if you have 28 psi with the comp not running at anything like summer ambient temps you system is seriously discharged, meaning a bad leak somewhere.

BTW, low side pressure, high side pressure... it's all the same when the comp isn't running. The whole system is at equilibrium and the pressure should be as indicated in the table linked below. But even if the pressure matches it doesn't mean your system is correctly charged. Like Octaneman said the surest way is to charge the exact recommended weight of r134a into an evacuated system.

http://dodgeram.org/tech/repair/HVAC/R134a.htm

nc37 · 06-27-2009, 09:39 AM

Thanks

nc37 · 06-27-2009, 09:41 AM

One more thing. I jumped the compressor as you stated. This allowed me to charge the unit. Worked fine for a little while, but we heard a small leak.

Took a sniffer and locate dthe source. It was coming out of the fromt of te clutch on the compressor.

I am assunimg that I will need a new compressor and clutch, correct?

**Raylo** · 06-27-2009, 07:33 PM

Compressor main seal is gone. The good news is that this kind of failure doesn't crap up the system so it can be a relatively simple job. The seal can be replaced but I've never done one. I just get a new comp. I also recommend a new vs. rebuilt compressor. This is within the realm of DIY if you understand it and take your time. Since the system is already discharged there really isn't any refrigerant to recover. If you go the DIY route look up your system specs and get the correct type and amount of oil and refigerant. Also should get a new orifice tube ans o-rings if you have this type of a/c. Vacuum pumps can be rented. A variabe: unless you flush the system you sort of have to guess how much oil is still in the system to figure how much to add. Good luck!

BTW, what is the vehicle?

nc37 · 06-28-2009, 10:21 AM

This is a 1996 Chevy S10 4wd.. 4.3 L V6

**octaneman** · 06-29-2009, 10:09 AM

Quote:

Originally Posted by nc37

One more thing. I jumped the compressor as you stated. This allowed me to charge the unit. Worked fine for a little while, but we heard a small leak.

Took a sniffer and locate dthe source. It was coming out of the fromt of te clutch on the compressor.

I am assunimg that I will need a new compressor and clutch, correct?

The front compressor seal can be replaced as long as you have the special tool to remove the clutch. like raylo said, it is better and cheaper to get a new or rebuilt one than doing the job yourself.

**Raylo** · 06-30-2009, 06:40 PM

Exactly... especially if you fix the seal on an old compressor it may just fail some other worse way, like a/c black death, in a year or 2 anyway....

I forgot to mention you MUST replace the accumulator, and SHOULD replace the orifice tube when you put in a new compressor. New compressors and accumulators generally come with seals and o-rings but the orifice tubes may not. So getting an o-ring assortment is a good idea. Don't forget the compressor oil. It should be specified on the compressor (probably PAG 150 for GM Harrison R134a system).

Again I recommend against reman compressors. They can be hit or miss. I once had one whose clutch pulley bearings froze up and stranded me after only 6 months of service. Not worth the $100 savings, IMHO.

Visit ackits.com or Rock Auto for parts and such. I have had good luck with both of these vendors.

06-25-2009, 05:41 PM	#1 (permalink)
nc37 Registered User Join Date: Jun 2009 Posts: 4 OS: XP	Help! My ac is not working.. My AC stopped working this morning. Thinking it may be low on charge, I stopped by autozone and picked up a can of 134A along with a gauge. The AC compressor is not kicking on. Thus, I can not add 134A since it can not flow into the system and just builds pressure on the connection. The presssure on the low side appears to be reading les than 28 PSIG. Question is: How can I make the compressor start and allow the refrigerant to be pulled into the system? Thanks

06-25-2009, 09:11 PM	#2 (permalink)
octaneman Mentor Home Support, Gearhead Automotive Center Join Date: May 2009 Posts: 564 OS: WINXP	Re: Help! My ac is not working.. Hi nc37 First thing you need to know if the compressor has not seized up. Check to see if the A/C belt is still on or slipping. In order to add the freon the system has to be evacuated and then checked for leaks. The only way to do that is with an A/C machine, once evacuated and no leaks appear, the compressor oil is added then the freon at 2.2 lbs. Check the fuse box for blown fuse, also look at the A/C controller to verify if power goes to it ,jump the pins on the controller to see if the compressor activates. Last edited by octaneman; 06-25-2009 at 09:21 PM.

06-26-2009, 07:38 AM	#3 (permalink)
Raylo TSF Enthusiast Join Date: Feb 2006 Location: Maryland, USA Posts: 525 OS: XP Desktop, Vista HP Notebook, XP Notebook	Re: Help! My ac is not working.. It is usually possible to charge a system w/o the comp running and get enough charge in to make the LP switch shut and start cycling the comp. There are some ways to help this along. You can also bypass the LP switch to make the comp cycle on early for charging. But from what we know here I would definitely not recommend it. Based on the r134a pressure/temp chart (see link below) if you have 28 psi with the comp not running at anything like summer ambient temps you system is seriously discharged, meaning a bad leak somewhere. BTW, low side pressure, high side pressure... it's all the same when the comp isn't running. The whole system is at equilibrium and the pressure should be as indicated in the table linked below. But even if the pressure matches it doesn't mean your system is correctly charged. Like Octaneman said the surest way is to charge the exact recommended weight of r134a into an evacuated system. http://dodgeram.org/tech/repair/HVAC/R134a.htm Last edited by Raylo; 06-26-2009 at 07:48 AM.

06-27-2009, 09:39 AM	#4 (permalink)
nc37 Registered User Join Date: Jun 2009 Posts: 4 OS: XP	Re: Help! My ac is not working.. Thanks

06-27-2009, 09:41 AM	#5 (permalink)
nc37 Registered User Join Date: Jun 2009 Posts: 4 OS: XP	Re: Help! My ac is not working.. One more thing. I jumped the compressor as you stated. This allowed me to charge the unit. Worked fine for a little while, but we heard a small leak. Took a sniffer and locate dthe source. It was coming out of the fromt of te clutch on the compressor. I am assunimg that I will need a new compressor and clutch, correct?

06-27-2009, 07:33 PM	#6 (permalink)
Raylo TSF Enthusiast Join Date: Feb 2006 Location: Maryland, USA Posts: 525 OS: XP Desktop, Vista HP Notebook, XP Notebook	Re: Help! My ac is not working.. Compressor main seal is gone. The good news is that this kind of failure doesn't crap up the system so it can be a relatively simple job. The seal can be replaced but I've never done one. I just get a new comp. I also recommend a new vs. rebuilt compressor. This is within the realm of DIY if you understand it and take your time. Since the system is already discharged there really isn't any refrigerant to recover. If you go the DIY route look up your system specs and get the correct type and amount of oil and refigerant. Also should get a new orifice tube ans o-rings if you have this type of a/c. Vacuum pumps can be rented. A variabe: unless you flush the system you sort of have to guess how much oil is still in the system to figure how much to add. Good luck! BTW, what is the vehicle?

06-28-2009, 10:21 AM	#7 (permalink)
nc37 Registered User Join Date: Jun 2009 Posts: 4 OS: XP	Re: Help! My ac is not working.. This is a 1996 Chevy S10 4wd.. 4.3 L V6

06-30-2009, 06:40 PM	#9 (permalink)
Raylo TSF Enthusiast Join Date: Feb 2006 Location: Maryland, USA Posts: 525 OS: XP Desktop, Vista HP Notebook, XP Notebook	Re: Help! My ac is not working.. Exactly... especially if you fix the seal on an old compressor it may just fail some other worse way, like a/c black death, in a year or 2 anyway.... I forgot to mention you MUST replace the accumulator, and SHOULD replace the orifice tube when you put in a new compressor. New compressors and accumulators generally come with seals and o-rings but the orifice tubes may not. So getting an o-ring assortment is a good idea. Don't forget the compressor oil. It should be specified on the compressor (probably PAG 150 for GM Harrison R134a system). Again I recommend against reman compressors. They can be hit or miss. I once had one whose clutch pulley bearings froze up and stranded me after only 6 months of service. Not worth the $100 savings, IMHO. Visit ackits.com or Rock Auto for parts and such. I have had good luck with both of these vendors.