2000 Blazer A/C Cooling Problem

[mrswans]

It has been about 90 and very humid here recently. On the last couple trips of 30 miles or so the A/C starts blowing hot for the last 10 miles. In town it seems to cool fine, but not as cool as normal. I checked the low side charge and it is close to 40 psi. I looked at the compressor when it was blowing hot and it wasn’t engaged. Any ideas?

Thanks,
Mike

[BlazerLT]

Did you test with AC on MAX with the fan on ful blast?

[mrswans]

Originally Posted by mrswans

It has been about 90 and very humid here recently. On the last couple trips of 30 miles or so the A/C starts blowing hot for the last 10 miles. In town it seems to cool fine, but not as cool as normal. I checked the low side charge and it is close to 40 psi. I looked at the compressor when it was blowing hot and it wasn’t engaged. Any ideas?

Thanks,
Mike

I checked the pressure with the A/C on Max and the fan on high.

[BlazerLT]

Check the low pressure switch if the compressor is not coing on.

[mike2004tct]

Originally Posted by BlazerLT

Check the low pressure switch if the compressor is not coing on.

Also look for the AC relay, I had a bad contact on mine. I found it by first hot-wiring the compressor to make sure it worked, then started tracing wires until I found the busted contact.

[mrswans]

Originally Posted by mike2004tct

Also look for the AC relay, I had a bad contact on mine. I found it by first hot-wiring the compressor to make sure it worked, then started tracing wires until I found the busted contact.

Hi, where would the relay be located?

Thanks,
Mike

[mike2004tct]

Originally Posted by mrswans

Hi, where would the relay be located?

Thanks,
Mike

Relay access door is inside the glove box. You should be able to swap the AC relay with the fuel pump relay, a quick swap will tell if it's a bad relay. Also inspect the wires at the block the relays plug into.

[mrswans]

Originally Posted by BlazerLT

Check the low pressure switch if the compressor is not coing on.

What is the easiest way to check it? Is the low pressure switch isolated from the freon?

Also, what is the connector that looks like a switch on the back of the compressor?

Thanks,
Mike

[mrswans]

Originally Posted by mrswans

What is the easiest way to check it? Is the low pressure switch isolated from the freon?

Also, what is the connector that looks like a switch on the back of the compressor?

Thanks,
Mike

Does the freon need to be emptied and recharged replacing the low pressure swithch?

[mike2004tct]

Originally Posted by mrswans

Does the freon need to be emptied and recharged replacing the low pressure swithch?

No. The switch fitting has a pressure bead in it,such that it can be replaced without losing any refrigerant.

[mrswans]

Originally Posted by mike2004tct

No. The switch fitting has a pressure bead in it,such that it can be replaced without losing any refrigerant.

Great, thanks

[mrswans]

Originally Posted by mike2004tct

No. The switch fitting has a pressure bead in it,such that it can be replaced without losing any refrigerant.

Replacing the low pressure switch fixed it.

thanks all

[BlazerLT]

Excellent!