A/C not engaging

[Tx Jim]

At rest, the low side is sitting around 59-60 and the high side sits to about 100. When I engage the compressor, the low side goes down to nothing and the high side goes up to about 150.
so I should add more R-134a until both sides equal out at about 150 psi at rest? I just don't want to add too much and blow something up.

I think somethings plugged on the inside(orifice/expansion valve) because with compressor off(at rest) the pressures should equalize no matter how much Freon is in the system.

 

[Orchardman]

G'day add some more charge with the comp running until you see 2-220 on the high side and see what happens you may have a blocked TX valve though

Oh and jumping the pressure switch will tell you if the rest of the elecs including the thermostat is working correctly as the comp should cycle on and off as it gets to temp


Jon

Hi Jon

Thanks for the reply, I imagine that I should put more charge in until it hits 2-220, but I guess I am afraid that the low side might get too high. From what I can see from charts posted about ambient tems/low side pressure. My pressure for the low side is already pretty high.

Also, im not up on my slang, what is a TX valve?

 

[Harry in Ky]

They are referring to the expansion valve. Your symptoms indicate it it either plugged or stuck shut. Sounds like you need to replace it.

 

[Orchardman]

A plugged valve makes sense. Everything was left open for a long time while I waited for the new compressor. Stupid question, but the expansion valve is probably inside my cab, right?

And while I am sure it is in bad form to complain about a company, to those of you who live in Washington, steer clear of Blueline Mfg. Happy to take your money, but you are outta luck after that.

 

[Harry in Ky]

Going back to your inital post - the comment about cleaning out the system as best you could should have raised a red flag. If you feel the need to clean the system while the compressor is out of the circuit, the expansion valve(yes, it's in the cab, at the inlet to the evaporator) should be removed and the system flushed in both directions. The high pressure lines from compressor outlet through the condensor and all lines(minus drier)up to the expansion valve fitting. Through the evaporator and suction line down to compressor inlet. Once the sytem is clean, then install the exp valve, drier, and connect the compressor. Any fittings removed should recieve new O rings(if they are O ring fittings), and then begin the evacuation and charging process.

 

[Tx Jim]

Orchardman
After having system left open for a while did you pump it down with an evacuation pump to remove air/moisture? If not the moisture could be freezing causing blockage.

 

[Loadstar]

You don't charge a system not running and say it's full unless you have a scale. Without a scale you are under or overcharged. There is no gage that says full for static charge.