Hit & miss with the A/C

[SIMid]

Hi everyone,

My A/C stopped working last time i drove her. Was blowing cold and just stopped. I spoke to someone at work and told me that she could be over gased. And yesterday, driving back from my work (they wanted to check her out), cold air kicked back in, ice cold and then went warm again. I can hear the fans running.

Any ideas before i seek professional help?

It's getting warm here in Melbourne now :(

[Michael]

Before going to the extreme of evac/recharge, try looking at a mechanical solution. It could be the mixture flap has come loose from the rod and is moving on it's own. It may also be a vacuum leak directing the air to the defrost, or floor and you may only assume it's going warm, when it reality, the airflow just changed.

Possibly a compressor switch or relay as well. Or maybe the pressure switch is not set right and the compressor cant cycle causing the ac to freeze up on you.

[Bitsyncmaster]

Next time it happens check the compressor and verify if the clutch is engaged. It may be your orifice is getting plugged and that would shut off the compressor.

An AC shop should be able to determine the problem when they put the gauges on it.

[TTait]

Or maybe the pressure switch is not set right and the compressor cant cycle causing the ac to freeze up on you.

how do you check the switch?

[SIMid]

Before going to the extreme of evac/recharge, try looking at a mechanical solution. It could be the mixture flap has come loose from the rod and is moving on it's own. It may also be a vacuum leak directing the air to the defrost, or floor and you may only assume it's going warm, when it reality, the airflow just changed.

Possibly a compressor switch or relay as well. Or maybe the pressure switch is not set right and the compressor cant cycle causing the ac to freeze up on you.

It gets warm in the car, so cold air has stopped.

Wheres the pressure switch Michael?

[SIMid]

Next time it happens check the compressor and verify if the clutch is engaged. It may be your orifice is getting plugged and that would shut off the compressor.

An AC shop should be able to determine the problem when they put the gauges on it.

I thought i'll ask here and iron out any bugs before booking her in for the checkup as a last resort.

[Michael]

It gets warm in the car, so cold air has stopped.

Wheres the pressure switch Michael?

The pressure switch is located on the accumulator and the adjustment is behind the plug. I can't remember which way to turn it to raise or lower the threshold. I adjusted mine a few years ago after having my AC worked on so the compressor would cycle like it should. I had to adjust it due to me changing the freon from R-12 to the newer "Freeze 12" and the higher pressure was making the compressor cut off too much. This switch should only be adjusted when you know the system has the correct amount of freon in it, and the pressures are where they should be.

[SIMid]

The pressure switch is located on the accumulator and the adjustment is behind the plug. I can't remember which way to turn it to raise or lower the threshold. I adjusted mine a few years ago after having my AC worked on so the compressor would cycle like it should. I had to adjust it due to me changing the freon from R-12 to the newer "Freeze 12" and the higher pressure was making the compressor cut off too much. This switch should only be adjusted when you know the system has the correct amount of freon in it, and the pressures are where they should be.

This is behind the passenger side front wheel?

Drove her today andnthe a/c blew cold all day. :( no idea what is going on here.

[Bitsyncmaster]

This is behind the passenger side front wheel?

Drove her today andnthe a/c blew cold all day. :( no idea what is going on here.

Then my guess would be an electical connection.
1) connector at the low pressure switch
2) connection at the mode switch
3) connector at the bulkhead.
4) wire connector at the compressor

[David T]

If it works some days and not others there are some possibilities. One is a very slightly low charge of Freon and depending on the ambient temperature it works or not. The other is that there is moisture in the system and when it freezes up in the orifice tube the system stops running. Another is a bad electrical connection that doesn't always work so your A/C doesn't work. Does your mode switch hiss?
David Teitelbaum

[SIMid]

Does your mode switch hiss?
David Teitelbaum

Yes it does David.

[David T]

Start with rebuilding the mode switch and maybe you will get lucky and it is just a bad contact inside and/or the leaky switch is not moving the actuators so it seems like the A/C isn't working as it should. That hissing is a vacuum leak.
David Teitelbaum