My AC was blowing warm air and the gas was low, 30 psi on Max AC. Added 3/4 can and psi is 43 on Max AC.
But when turned on the compressor spits from the bottom side, it is real loud. It never did get cool air.
Is the spitting a pressure relief?

 

How did you add 3/4 can if the compressor was not on?

 

The compressor was on??
The clutch was cycling off/on rather quickly but after adding the freon, the comp. clutch pulled in and stayed on more than off.
There is some kind of port on the bottom side of the comp. from where the 'spitting' comes from.

 

Not an A/C expert at all here........but I've never heard of any spitting like that.......sounds like it may be why you were low........leaking
One way to find out is run it a while.......if it starts cycling on and off again......it's leaked out.

Good Luck

 

The compressor is having its relief valve open from to high of suction pressure. 30 psi is about right. It sounds like your having other problems, like a damper in the duct that is in the heat mode.

 

How can I check the damper in the duct??

I have noticed that the contents in the glove box are always hot after driving the truck, even when I dont use the heater.
Does hot water flow through the heater core even if the heat is not turned on?

Thanks

 

Yes, it does. There is no valve to keep antifreeze from flowing through the heater core. The blend door just varies the amount of air flowing through the coils of the core and the A/C coils, from full through one to full through the other.

Jason

 

The relief valve is on the High Side not the Low Side.
30 PSI is too low for the Low Side and if you added a can and still have 30 PSI on the Low Side with the relief valve opening on the High Side then you have a blockage going into the evaporator. Maybe Ice or garbage blocking the Fixed Orifice Tube.

Pressure Relief Valve
A pressure relief valve is installed on the compressor discharge manifold to relieve excess high pressure buildups (310 kPa or 450 psi and above) and prevent damage to the compressor and other air conditioner components.

I do not know if the Pressure Relief Valve has a rupture disk or it is spring-loaded. In either case it may have to be replaced if the high side pressure is below 450 psi and it is leaking.

 

Would it hurt anything if I put a ball valve in the heater hose line to prevent hot coolant from flowing to the heater core? Just for the hot season and open it in the cool season.
It gets hot in the glove box where I keep a S&W 686 and I don't like the idea of the ammo getting heated up.

 

Yes you can put a valve on it and it will not hurt anything.
Also the vans use a vacuum controlled valve to turn it off while the A/C is on. You may want to go this route.

 

Yeah I'm sorry I meant head pressure. I agree that 30 psi is not ideal, but it should be cooling. My initial thought was a possible blockage, but without a high side reading its hard to know for sure. I think for the money (relatively cheap) that putting a shut off valve in the heater hose would be a good trouble shooting guide. Is there a filter for the evap in these trucks? I'm not as familiar with what stuff they put in a truck. I've worked on refrigeration & heating & cooling for 12 yrs. I do know that most blockages in a car seem to be from metal from the compressor. I hope he can figure it out.

 

Thanks to all of the responses.
Now I have enough info to get started, again.