98 expy 5.4 A/C

[fourty03]

I have a question about my a/c system.

When I bought the truck, I found the low pressure switch hacked up and the wires twisted together. This enabled the compressor to turn on regardless of the amount of refrigerant in the system.

I put everything back and repaired it.

Now, when I turn the ac on, I get warm air (or whatever the ambient temp is outside. The compressor is on when I turn the ac on.

The tube from the compressor gets hot (assuming this is the high pressure side) and the other tubes are cold.

When I turn on the rear ac, I get the warm air too. I then took the kick panel off where the blower motor and heater / ac lines are. The ac lines in the back are so cold, it started to freeze within a minute or two after turning on the system.

Here is the rear

The line that has the green line was frozen. What is the metal block component ?

Also, I'm assuming the system is tight due to the pressure it retains when pushing on the shraeder valve (both high and low side). I don't have the funds to get a gauge yet and am just looking for more in depth info on what could cause my ac issues.

Thanks!

 

[stamp11127]

That block is called an expansion valve. It is a variable valve that adjusts to the temp of the refrigerant.
One indicator of a low refrigerant level is a freezing line.

The low pressure switch was "jumped" because the pressure was dropping too low and stopping the compressor from working.

You have a leak in the system, finding out where is cheap & easy if you have the tools. Expensive if you don't. Another possibility is that the compressor has trashed itself and plugged the orifice tube and expansion valve. You won't know until you have the low and high side pressures.

 

[fourty03]

Thank you 'stamp..

I have no history on this truck, and I'm almost afraid to find out why the previous owner bypassed the low pressure switch.

I've read a lot of material on the forum concerning the 5.4s and 4.6 engines and I cannot be patient enough to get the proper tools.

My school has a big discount on Snap-on tools, Mac, Matco .. All around up to 60% off... But unfortunately, tools will have to wait until I get my finances in order.

Again, thank you.

 

[stamp11127]

Since you mentioned school, most automotive or diesel schools have the a/c machine available to the students. I would ask around and see if they will at least hook up the expy to see what the pressures are.

What are you taking in school? About 2 years ago I went through a diesel/heavy equipment course as a career change.

 

[fourty03]

I actually am doing an A.A.S. in automotive. We cannot use the tools and equipment for our personal cars unless it has something to do with the class were currently taking.

I've done electrical, suspension, brakes.. I'm in basic engine this semester.. I go to a community college.