Jmac

My buddy is using my truck to haul a load of watermelons up north and while accelerating on the on ramp to the interstate the A/C compressor quit working. My first guess was a blown fuse or a relay switch. Any and all thoughts would be greatly appreciated.
Jamie

imbodie

I'd be checking coolant/freon/whatever it is.....
If there is not enough "freon" in the system it will not allow the compressor to kick in. You can get coolant and pressure guages at wallyworld for less than $30. I would only try adding ONE can to see if it fixes the problem...
Just a thought.
-Tim

Jmac

If there's not enough freon then that means there's a leak? Would a fuse/relay switch cause it to not work.
thanks jamie

imbodie

I'm sure a fuse or relay could cause problems. I still think checking "freon" pressure would be the best first place to start. There is a pressure switch on the coolant system that would detect "too low" a pressure and not let the compressor engage. I just checked mine last week and added a whole can to the system. It was showing a little low. So I've averaged a can a year because I did the same thing this time last year.
-Tim

1-2-3

Fuses don't quit then work again. Two things usually happen. Blend doors and low freon. I'd guess low freon, meaning a leak. You can recharge it with a Wally World kit but if there's a leak, it'll happen again. Leak test is usually the best. Get it found and fixed then recharged. Still have any warranty left?

madhat

Don't rule out the high pressure switch. If you throw a can in there, and it is empty in about 5 seconds, then you have a leak.

If you hook a can up, and nothing happens, then you might be over pressurized, and need to look elsewhere.

Don't go shotgunning (throwing) parts at it... it can get really expensive, quick. Make sure to diagnose the problem correctly before you start putting big money into it.

annabelle

Does it still blow air? Mine will freeze up and only blow warm air in high humid conditions. I have seen a tread about moving a temp. sensor.

Jmac

still blows, just not cold. is there a cheap way to pressure check?
jamie

imbodie

$25 at wallyworld will get you a can of refrigerant and a guage. Someone else mentioned their system would freeze up, and I've always been told that a freezing coil meant low refrigerant....

Again, just thoughts, I really know nothing about AC systems.
-Tim

ado2b1

When you get 134a, don't get the stuff with the oil in it, you don't need it, its also about half the price. Don't waste any money on dyed stuff for detecting leaks, or the leak sealer. Its pretty much all useless. On diagnosing, see if you have a buddy with a gauge set, or if your autoparts store has a rent-a-set. That way you can check you high and low side and diagnose any problem with the system (including if your compressor is going bad).

As far as a leak, the way these (and most other systems work) is they function properly until the critical pressure is not detected then stop in their tracks. It could have been low for years with a very slow leak, and its just now stopped. Mine leaks an ounce or so a year. Not nearly enough to replace and fix compared to a $4 can of refridgerant.

If its low enough, it may take the compressor a while to cycle on and off and pull it into the system. Don't overcharge it, though its pretty difficult to do anyway.

BTW. You don't have to get the can with the el cheapo gauge and hose. Get a separate hose at oreilly's or somewhere and ASK for the cans with no oil (at mine they keep that stuff off the shelves because its uber-cheap compared to the other products).

Jmac

when we hooked up the pressure guage to the system it pegged the needle. so can i assume i don't have a leak? If that's correct, then what's causing the air from blowing cold?
thanks jamie

imbodie

Ok... how can you check your compressor with guages... Teach us....

Seriously...

-Tim

imbodie

At this point I would be taking my truck to a shop I trusted. If you expected a low reading and got a pegged needle, you either connected to the wrong port (didn't think this was possible) or have something a bit more serious than low refrigerant pressure. Possibley a bad pressure switch (you can jumper it JUST to see if the compressor is working) or maybe a compressor/clutch going bad (would think there would be a lot of noise with this possibility).

Haynes has a great little manual for ac/heating issues. It's blue and can be found with all the other manuals at Autozone. Looks like I'm going to dig mine out and read it again tonight just to get a better grasp on how to use the guage sets if nothing else.
-Tim

J BODY

I'm patiently waiting........I'm guessing it has something to do with the driver.

imbodie

That is always an option.... blame it on the driver and let them go have it fixed at the BEST shop in town.

I should have thought of that.
-Tim