Ac low side pressure

[silky28]

hey all,

So after returning from overseas and preparing the 2003 Hoe for a long road trip I found the AC not functioning. I added 3 cans of r134a which got the condenser running on its own and the truck cooling...but it is not cold. With recirc on the lowest temp I saw was 50f at the vent.

What pressure should the low side port read? Using the cheap gauges that cam with the refill kit I got the pressure to about 50psi with the pump running with ambient temp of 80f. Is that about right?

I am also having a problem with the relay for the ac. I have to sit of angle the relay or bend it a bit to get contact to run the compressor. How would I go about fixing that?

 

[swathdiver]

hey all,

So after returning from overseas and preparing the 2003 Hoe for a long road trip I found the AC not functioning. I added 3 cans of r134a which got the condenser running on its own and the truck cooling...but it is not cold. With recirc on the lowest temp I saw was 50f at the vent.

What pressure should the low side port read? Using the cheap gauges that cam with the refill kit I got the pressure to about 50psi with the pump running with ambient temp of 80f. Is that about right?

I am also having a problem with the relay for the ac. I have to sit of angle the relay or bend it a bit to get contact to run the compressor. How would I go about fixing that?

@gpracer1

 

[TheAutumnWind]

Stop guessing and get some real manifold gauges. You already spent more on r134a then a set of gauges would cost you most likely.

50psi on the low side is high for 80*F I believe.

should be like 30 to 45psi

Im guessing that you didn't pull a vacuum on the system? It must've been completely empty if you put 3 cans in or you overfileled.

 

[SnowDrifter]

Of note, this chart should be used for diagnostics not final fill. The appropriate way to do that is to fill by weight.

I assume you leak checked the system, held a vaccuum for 30 mins to dry, then filled by weight?

 

[silky28]

Sorry...thought I had responded to this.

So I hooked up the manifold gauge to get the high and low side pressures and this is what I go. Low side pressure was ~50 psi @ 90 degrees (which seems fine) but the high-side pressure is low at ~ 175psi. Not sure what to make of that.

I drove through Texas...along the Mexican border...where it was 105 degrees the AC blew cold but not as cold as it has been in the past, but when stopped the AC blows much warmer. I've checked the fan clutch but its tight and seems to be working a sit should.

 

[SnowDrifter]

50/175 at 105 degrees?

Sounds almost like the compressor might be worn out / clutch slipping / belt slipping

 

[TheAutumnWind]

How clean is the condenser? Is your radiator shroud in good shape?

 

[SnowDrifter]

How clean is the condenser? Is your radiator shroud in good shape?

I'd think that would cause an excessive high side pressure, not a low, high side pressure

 

[silky28]

How clean is the condenser? Is your radiator shroud in good shape?

I replaced the condenser last summer (along with all the lines, valves, seals, dryer and seals) and it still looks basically new. Shroud is fine.

 

[live2pull]

Have you checked your schrader (service port) valves for leaks?