A/C compressor not cycling
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A/C compressor not cycling
I have a '96 Dakota 6-cyl.With the weather getting warmer I turned on the a/c the other day and the compressor didn't cut in. The fuse is OK.I'm not familiar with a/c servicing but was thinking maybe it's lost its refrigerant charge over the winter months. Would appreciate if somebody could give me some basic suggestions for troubleshooting.Money's tight and I hate to pay a service guy for something I could tweak myself. Thanks in advance.
Champion
Joined: Dec 2003
Posts: 4,119
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From: Sycamore, Illinois (displaced to Arkansas)
RE: A/C compressor not cycling
It's a fairly simple system, actually.
A signal is sent from the "A/C" switch, and if two pressure switches aren't tripped (the low pressure switch, which is located on top of the accumulator/drier [passnger side firewall] and the high pressure switch [located right by the compressor]) the signal is sent to the PCM, which than provides a ground for the compressor relay.
Switched power (to turn the relay "on") is provided from the ignition switch. And, power is provided from the battery.
Simply put, its probably just caused by a low refrigerant charge. These kits are available at any auto parts store (or WalMart).
If adding a charge doesn't help, try swapping the relay with another known-good one.
And if that doesn't work, try manually bypassing the pressue switches (unplug the connector and put a jumper wire between the terminals).
Post back with results.
A signal is sent from the "A/C" switch, and if two pressure switches aren't tripped (the low pressure switch, which is located on top of the accumulator/drier [passnger side firewall] and the high pressure switch [located right by the compressor]) the signal is sent to the PCM, which than provides a ground for the compressor relay.
Switched power (to turn the relay "on") is provided from the ignition switch. And, power is provided from the battery.
Simply put, its probably just caused by a low refrigerant charge. These kits are available at any auto parts store (or WalMart).
If adding a charge doesn't help, try swapping the relay with another known-good one.
And if that doesn't work, try manually bypassing the pressue switches (unplug the connector and put a jumper wire between the terminals).
Post back with results.
Rookie
Joined: Nov 2007
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RE: A/C compressor not cycling
Last year I was having a/c problems. My air coming out was cold but the ambient temp in the truck never cooled down. I just figured I was a little low on 134a. That didn't help. The ac compressor was cycling in and out pretty quiclkly. On for about 10 or 15 secs then off for for the same. if you direct the vents on you it would keep you cool.I need to replace a relay but I'm not sure where it is. If you happen to know where it is by the time you get yours fixed, I would appreciate if you would let me know. THX
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Registered User
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RE: A/C compressor not cycling
Thanks for your responses. Just waitin' on the 1st of the month (retired Navy payday 
) to see if a charge solves the problem. I don't feel comfortable trying it myself.
Alterboy, when my a/c is working properly it cycles at about the same rate you're seeing with yours. Last time I got it charged up it worked like a champ, crank it up on a warm day and five minutes down the roadit's like the North Pole. Thea/c clutch relay isin the Power Distribution Center (PDC) box in the engine compartment (driver's side) The other two controls are thehigh/lowpressure switches that Dodgerules85 mentioned above. I'll post again when Italk to my service guy.
-Jerry
) to see if a charge solves the problem. I don't feel comfortable trying it myself.Alterboy, when my a/c is working properly it cycles at about the same rate you're seeing with yours. Last time I got it charged up it worked like a champ, crank it up on a warm day and five minutes down the roadit's like the North Pole. Thea/c clutch relay isin the Power Distribution Center (PDC) box in the engine compartment (driver's side) The other two controls are thehigh/lowpressure switches that Dodgerules85 mentioned above. I'll post again when Italk to my service guy.
-Jerry
