A/C not working

twanger1994 · Jul 1, 2006

I believe ive seen commercials on tv from national chain mechanic shops that offer a free check and diagnostics of the a/c system. I just dont remember which one. maybe most of them offer it. So where should I take my car to let them check it out. thnx mike

p.s. what are some of the common things that go wrong on an ac system. i believe that my compressor is shot. How can i test it.

4Jenna · Jul 1, 2006

Try jumping the switch in the back...very common
Has the plug connector going to it
Low press switch or something, if you jump it and it blows cold..wa-la change the switch

braxx · Jul 1, 2006

Not always the case. That is the low pressure switch. If your system is just low enough on r134, the low pressure switch won't let the compressor kick on. If you "jump" the switch, it will force the compressor to come on (That is if the problem was just a low amount of r134 or a bad switch) and even blow a little cold if the system is just a little low.
I have a 2000 F-150 and this year the air wasn't cold (actually wouldn't come on) I jumped the switch and I got cold air. Normally, people would think it was a bad switch. I brought my truck into my work and hooked it up to a awesome new A/C recylcer / do it all machine. After letting it do it's magic, it gave me a print out. I had 1.79lbs of r134 in the system that it reclaimed BUT my truck takes 2.08lbs to have a full charge. So, it was about 10% low. That was low enough for the pressure switch to sense a problem and not let the clutch on the compressor cycle. BUT over all it was still enough in the system to blow cold air if you jumped the switch.

eades5.0 said:
Try jumping the switch in the back...very common
Has the plug connector going to it
Low press switch or something, if you jump it and it blows cold..wa-la change the switch

HISSIN50 · Jul 1, 2006

Braxx is right about the possibilities. One needs to trace the electrical side of things (starting at the LPS) if the clutch isnt engaging.

If you get it to engage, toss your manifold gauges on it and see what it reads with the clutch engaged.

Cant help with the chain store testing, though I think that's a decent idea. If they accurately diagnose it, we can help ya fix it.

Good luck.

twanger1994 · Jul 2, 2006

thnx ill check that all out. and get back to yall

just to give everyone a little insight to my dilema

ok I turn om my ac nothing but hot air... I checked the r134a cause last year it was low. (I think i had a leak) recharched it with leak stop and it worked fine all summer. Northeast doesnt have much use for ac in the winter months so again it was left off. Till the heat broke and all I have is hot air blowing. So I thought to recharge it again thinking it was a little low again. Not the case, it was full, and not over full either. So I started looking into electrical things, the switch on top of the accumulator is good, I have not checked the low pressure switch yet but im almost positive it will not make the compressor kick on or the clutch to grap. As for right now the compressor spins just as it should when not in use. Hard to say if its the clutch or compressor. I am limited in knowledge of ac stuff. thnx let me know if you need to know anything else

HISSIN50 · Jul 2, 2006

If the clutch doesnt engage, how do you know what PSI is in the system? When AC is off, you'll see a fairly high transient low-side reading.

WHen you jump the LPS while your manifold gauges are connected, what are you reading?

That'd help narrow down if it's a charge or switch issue.

Good luck.

twanger1994 · Jul 2, 2006

how do i get to the switch do i have to take anything off the back of the compressor???? thnx for the info

99FiveOh · Jul 2, 2006

Pull the plug off the switch that sits on top of the accumulator, then take a small length of wire or a paper clip and make a jumper. Jump the two terminal to eachother and fire up you engine and A/C to max. If your compressor comes on it's that switch. If it does not kick on check the plug that goes into the compressor. if it's plugged in then your clutch is probably bad. My sister's F150 just had this problem and some shop cleaned it(the clutch) out for free and it started working again!

Also, try to spin the face of the compressor (not the pully) and tell us how it spins, loosely or does it have resistance.

HISSIN50 · Jul 2, 2006

The_Mustang said:
Jump the two terminal to eachother and fire up you engine and A/C to max. If your compressor comes on it's that switch.

I'd say it can also be a low charge (and the switch is doing just what it should and safeguarding the system). Would you disagree?

Methodical · Jul 2, 2006

HISSIN50 said:
I'd say it can also be a low charge (and the switch is doing just what it should and safeguarding the system). Would you disagree?

I agree with you Hissin. According to the shop manual, you 1st jump the low pressure switch and if the clutch activates you then must check the system's pressure. If the pressure is between 25-45lbs then replaced the AC cycling switch (or low pressure switch).

To the original poster, there's been many AC post recently including mine. Do a search and see what you find out but it's most likely either of 2 things the AC cycling switch or low on freon

Either way please post the results.

99FiveOh · Jul 3, 2006

I'm sorry, I wasn't thinking right. What I should have said is that if the compressor comes on, it rules out the compressor as the problem.

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