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AC compressor not engaging

26954 Views 13 Replies 6 Participants Last post by  Cusser
First world problems, right? AC not working in winter? It was working fine a few days ago (isn't everything that breaks working fine?) No signs of anything bad happening, no squeals, no smells, nothing. I recently moved back to Colorado from being in Vegas, so I'm thinking it didn't like the trip. It is a 2007 frontier with 105k miles.

I can cycle through all the speed settings on the blower just fine. AC light comes on but I can't feel or hear the compressor engage. I checked the fuse under the hood and it was good (10 amp fuse). I checked for code and there's nothing, no pending and no stored codes.

I didn't smell anything when I was down there with the engine off and with it on with the AC on. I didn't see any fluids or anything.

Now, when I was in Vegas I dont know if it was the heat or what, but the AC would be cold, but not THAT cold. Say it was 110 outside, the inside of the cab would be 85. Maybe 80. Could I just need a recharge? I was under the impression the AC system was sealed and the only time a recharge is necessary is when there's a leak.
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You could possibly have a slow leak, at 10 yrs its possible some o-rings are getting brittle/worn. So a pressure test would tell you if its good or not. Also the compressor clutch could be bad, or the relay feeding it. Try enabling it directly, like with a Power Probe... When I get home I'll look up the circuit.
I don't have a power probe. Would a paperclip work? I have 2 paperclips.
I'd get the free loaner gauge set from Autozone, and measure the R134a pressure. I'm thinking that you just had some normal R134a attrition over the years (the system is designed to leak a tiny bit at the compressor seal, to keep that lubricated), and now your system is too low to actuate the compressor, for safety. Your comment on the below-standard cooling prior to this seems to corroborate this. My experience with my '98 and 2004 Frontier AC systems in Arizona is that they perform GREAT.

My 2004 Frontier just needed - for the very first time this summer - R134a top up. Remember - NEVER add any sealer or refrigerant containing sealer. UV dye is OK to add though.
I'll just take it to a shop and have them top it off. We have a guy here my family uses that does honest work.

So the AC system is actually designed to leak a tiny amount?
Is there a way I can manually engage the compressor to make sure that still works?
I don't know where your at in CO but the altitude difference from Vegas alone was probably enough to affect your pressures enough not to run plus being on a 10yr+ pickup go get gauges an some freon without sealer so you can look or just run it by a shop at least you'll know where you stand

And yes but just so you know there are risks associated with it like ruining your compressor IT needs oil when it runs that's why they PUT the switch there so if you have a leak or it's low it doesn't energize the clutch to damage your expensive compressor

And NEVER repeat NEVER stick any of those can with leak sealer in when your charging unless you like to throw money out having to evacuate system to replace a clogged orifice or worse just make sure you read the can most of the ones in the stores you know Autozone Orielys have a sealer the one without is smaller sized like your coffee mug and on bottom shelf @walfart I think its like $6 plus a hose 8-10 but doesn't tell you your H/L pressures you can get one with a simple gauge to tell you the low side pressure IDK if they sell it separate but they sell em in a kit and you can just throw the can that came with it away if it has sealer never said it be easy or cheap

With car running with a/c control on jump the low switch on line should engage good luck

I was under the impression that if you're refilling the A/C the compressor needs to run in order to circulate what's being put in. That's why I'm curious about engaging it. Or am I wrong and the compressor doesn't need to be running?
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