A/C problems update-6/24

[shortstuf212559]

okay i had posted this over on BC prior to the change over so i'm gonna repost it here now.

i have no a/c. my compressor clutch will not engage at all. the RPM's change when i press AUTO, there is 12 volts at the compressor connector. i have tried overriding low pressure switch by bypassing it, but still no compressor clutch engaging.

is my compressor dead then?

[wjcollier07]

do you have the proper amount of refrigerant in the system? it won't engage unless you do.

[fastblackbeauty]

do you have the proper amount of refrigerant in the system? it won't engage unless you do.

Also shouldn't engage if the refrigerant is bad...or needs changed.

[wjcollier07]

well..changed? dunno about that. the orifice tube and the accumulator take pretty good care of that. but regardless of its function..is the system still R12? If so, it needs to be retrofitted, you're gonna have a *dang* hard time finding R12. You'll need to clean the lines out with flushing solvent, replace the orings, orifice tube, accumulator and compressor.

[TampaSSeI95]

my ac clutch wont engaged but if i hit it with something it will kick on. same problem or do i need a new clutch?

[shortstuf212559]

the system was retrofitted by a pontiac dealer in 2005 to R134A. The system is fully charged.

[clm2112]

the system was retrofitted by a pontiac dealer in 2005 to R134A. The system is fully charged.

Ok, well, there's a switch on the accumulator (aluminum can on the firewall) that causes the system to cycle. If the switch goes bad, the power never gets applied to the compressor clutch. In addition, there are a pair of relays, plus and over-pressure switch on the back of the compressor (round, 2-prong connector). Failure of any one of them will cause the compressor clutch to not engage.

If you have a voltmeter, you can connect up to the compressor clutch (2 prong connector just behind the pulley of the compressor) to see if you are getting any power applied to the clutch. I presume the clutch is not engaging..i.e. the system never "clicks" on spinning up the compressor off the accessory drive belt?

The way the system works is pretty simple..

1.) You select one of the settings on the controls that turn on the A/C system. That activates the first relay to turn on the compressor clutch circuit. (Relay center under the dash)

2.) The output of the relay goes to the compressor high pressure cut-out switch on the back of the compressor. This switch should always be closed as it is just a safety to shut off the compressor if the system pressure get's too high.

3.) The output of the safety switch goes to the pressure cycle switch. This switch closes at low pressure, and opens at high pressure. The system is an orifice tube system.. the compressor pumps up the pressure to a high level, then get's shut off until the pressure bleeds down through the orifice tube. When the pressure drops low enough, the switch closes to make the compressor pump the system back up again. Over and Over.

4.) The output from the cycle switch gets passed through a second relay the ECM controls (A/C cutout Relay on the firewall)...giving the car's computer an ability to shut-off the AC system if it needs the power to run the car.

5.) Last stop for the power is the actual compressor clutch. Power applied locks the two parts of the pulley and allows the serpentine belt to spin the compressor's guts.

If you have some kind of refridgerant in the system, then it should cycle if all the connections are good. It may not get cold, but it will cycle.

Another quick test is to briefly jumper the contacts at the cycle switch. That should turn the compressor on. If it doesn't, time to start tracing down the wires.

A common place where a failure occures is the connector that plugs into the compressor clutch. It get's hard and brittle after years of being cooked by the engine heat and can simply fall apart.

[shortstuf212559]

i checked and i have 12 volts at the compressor connector

[clm2112]

i checked and i have 12 volts at the compressor connector

Ok, then the system is trying to cycle the compressor clutch and the clutch is not engaging. Reseat all of the connectors just to be sure you have enough current to engage the clutch, and if it still doesn't kick in, then the clutch is probably dead.

You can also disconnect the clutch connector and apply 12vdc from the battery directly to the clutch contacts (engine not running of course, for this test you are just listening for an audible "CLICK" when the clutch engages, you don't need to have the motor running to do this.)




If you find the clutch is dead, you can replace the clutch alone. However, you run the risk of damaging the seals on the compressor while doing this and may have to scrap the compressor for a new one.

[shortstuf212559]

Okay so i took a close close look at the conector and found one of hte pins to be smashed down flat. now i bent it back up and replugged it in and now my compressor is cycling on and off (my system has no charge at all. as i went to give my system a charge i have found a very bad leak. i think it is coming from the condensor as it was coming from behind the radiator. the freon goes out as fast as it sucks it in...

[clm2112]

Okay so i took a close close look at the conector and found one of hte pins to be smashed down flat. now i bent it back up and replugged it in and now my compressor is cycling on and off (my system has no charge at all. as i went to give my system a charge i have found a very bad leak. i think it is coming from the condensor as it was coming from behind the radiator. the freon goes out as fast as it sucks it in...

Cool, half the battle solved, the condensor is available from many sources. You probably took a rock into it. There's really no way to repair it, it just goes in the trash and replace with a new one.

[BlackHawk99]

When you replace it, make sure all the joints are sealed well. Then, pull a vacuum on the entire system for a minimum of two hours. If you can go longer, great. All the moisture MUST be removed from the entire system before you recharge it.

[shortstuf212559]

well i just ordered one of those vacuum things from harbor freight and a manifold gauge set. i ordered the condensor from autozone, 109.99 for the heavy duty cooling, ouch. everythign will be here by wednesday, and hopefully i'll have working ac asap

[shortstuf212559]

well i've got the new condersor in now, and just awaiting the vacuum pump to come in the mail... hurry!