No A/C in the summer heat...

[Parentnoia]

Middle of last summer, my A/C stopped working. Didnt worry much about it because we didnt have the money or means to save up. Now that summer is coming back around, we're going to need it. The A/C had one problem before it stopped working. It was constantly on if the A/C button was pressed, even if the fan was off. Is that normal? I dont seem to have an air off at all. With the fan off, I get air through the vents as I drive and it changes temp with the knob.

Anyways, after awhile, I noticed that the engine no longer get's loaded down when I press the A/C button. How do I check to see if I need to replace the A/C all together or just need to recharge it?

 

[Half Assed]

Sounds normal to me. If the a/c button is on, it's going to be on.

Check to make sure the a/c clutch is kicking on. Get some cheap A/C gauges from a friend or from harbor freight for $40. Low side should be around 35 psi. High side should be around 200 if I remember correctly. If is kicking off and on quickly, that is a sign it is low on freon. If the low side is lower than 35, it's going to freeze up before it reaches the evaporator which means you get warm or cool(not cold) air from the vents.

The compressor is well known for being a leaky POS. So it might be a good idea to put some UV die in it and check for leaks in the whole system. If there are no signs of leakage I would put a can of r134 in it and see what happens. If it holds then you should be okay, but I have a feeling you probably have a slow leak. If the compressor is bad, spend a little extra for a sanden compressor. They are redesigned so that they don't leak in the middle of the case. Don't cheap out and get a chinese compressor, it will fail.

I had a similar problem a few weeks ago, it turned out to be a leaky port valve on the low side.

The big problems I think people have on a/c is a bad compressor, bad clutch or pressure switch, clogged orifice, or a slow leak. The bad thing about A/C is that in order to work on it you almost always have to pull all the freon out first before you can replace parts and then put it on a vacuum to seal it all up again.

 

[1997chevydriver]

With the button staying lit up when pressed and fan in the off position your fan speed switch is warn. I replaced mine and now it won't come on till i turn on the fan.

 

[SAATR]

With the button staying lit up when pressed and fan in the off position your fan speed switch is warn. I replaced mine and now it won't come on till i turn on the fan.

That's the way it's supposed to work, with the fan switch shutting everything off if in the off position. I don't know if you can just replace the rotary switch or if the whole control head has to be replaced, but that would be the fix.

Parentnoia: You need to do as Half Assed says and connect some gauges to the system to see if it's out of refrigerant or simply not kicking the compressor on when you turn the AC on. It is entirely possible that you just have a control head failure that isn't signaling the compressor to turn on. If you have around 80psi on both the high and low pressure ports when the AC is turned off, then it should be charged enough to allow the compressor to kick on. If you have low pressure or no pressure, then the issue is probably a leak, again as described by Half Assed.

 

[oohunter04oo]

With the button staying lit up when pressed and fan in the off position your fan speed switch is warn. I replaced mine and now it won't come on till i turn on the fan.

fan speed switch? Link? you mean the blower motor resistor?

 

[SAATR]

fan speed switch? Link? you mean the blower motor resistor?

The rotary switch that the is connected to the knob, I believe.

 

[1997chevydriver]

You can replace just the switch, well at least on my 97 you can. Bout 20 bucks from the parts store. Im talking about the switch you turn with the knob

 

[great white]

Is the compressor clutch engaging?

Is it short cycling?

 

[Parentnoia]

Is the compressor clutch engaging?

Is it short cycling?

Just noticed the reply.

How do I check that?

 

[1997chevydriver]

Just noticed the reply.

How do I check that?

Turn ac on and open the hood and see if the center part of the ac.pully is spinning