AC compressor question

[fishEH]

What is the circled piece and what would cause it to blow? Is it replaceable?


I'm using my AC compressor as an OBA system, so no refrigerant involved. Can I just plug it?

 

[Rover from hell]

Pressure relief valve ?

 

[robertf]

thats my guess too. Probably the mechanical backup if the other parts fail when the evaporator freezes so that it doesn't dump in the passenger compartment

 

[fishEH]

So what's that thing designed to vent at?? I have a blowoff valve in the system at 145psi and it didn't blow, so I'm wondering why the AC compressor one did??

 

[robisonservice]

So what's that thing designed to vent at?? I have a blowoff valve in the system at 145psi and it didn't blow, so I'm wondering why the AC compressor one did??

I'm not sure what you mean by that statement. No car is made with a 145psi safety valve because summertime pressures can exceed 300PSI. The typical safety valve opens at 400psi or more, and it's located on the compressor. There is no other common location for auto AC safety valves.

The usual reason for excess pressure is a clogged expansion valve. That produces way too much pressure on the high side, a vacuum on the low side, and no cooling. Left alone, it will destroy the compressor. The usual cause of expansion valve failure is clogging with debris from a failed receiver drier. In that manner, drier, expansion valve and then compressor often fail in cascade. If the safety valve does not open you can blow the condenser or high pressure lines too and that leaves you a $2000+ repair bill

 

[cupgt]

He has a 145psi blow off because it is setup for on board air using the AC compressor.

 

[fishEH]

Ahhhh, thank you. I'm attempting to turn my AC compressor into an On Board Air set up.
I have the Low side set up as an intake with a prefilter and an in line lubricator. The High side is my output and goes to a dryer/separator, regulator, etc.
Can I remove the expansion valve and just run the compressor as-is? The system is set to kick on at 90, off at 120psi. I wonder if that expansion valve is restricting my air output too?

 

[robisonservice]

If you want to run the system as an air compressor the expansion valve should be removed and an air filter/oiler setup fitted in its place.

 

[fishEH]

If you want to run the system as an air compressor the expansion valve should be removed and an air filter/oiler setup fitted in its place.

Ok, thank you. And this expansion valve is located inside the compressor? Just tear it apart and I'll find it I assume?
What can I do about the relief valve that has blown?

EDIT: The RAVE shows the expansion valve as a completely separate unit. If that's the case then it has been eliminated from the get go. No part of the original AC system is being used except the compressor itself.
So I'm still left wondering why that relief blew like that.........

 

[ERover82]

Plug it and see what happens. Make sure to video..

 

[fishEH]

Yeah, no. I'd like to find out WHY it blew like that if the expansion valve was out of the picture and the pressure switch I installed disengages the clutch at 120psi. I have another AC compressor on my bench but I'd rather not break that one before I understand what happened to this one.

 

[jafir]

Yeah, no. I'd like to find out WHY it blew like that if the expansion valve was out of the picture and the pressure switch I installed disengages the clutch at 120psi. I have another AC compressor on my bench but I'd rather not break that one before I understand what happened to this one.

the expansion valve is in the evaporator box. If you aren't running the compressor through the evaporator anymore, you aren't going through the expansion valve.

 

[fishEH]

Hmmm, I wonder what the he'll is going on then? Could the compressor be building 400psi inside itself before the regulated side disengages the clutch at 120psi?

 

[jafir]

I wonder what it's made out of? Maybe temperature affects it? Maybe it's running hotter than an A/C system would, and maybe that causes it to pop earlier?

 

[fishEH]

I wonder what it's made out of? Maybe temperature affects it? Maybe it's running hotter than an A/C system would, and maybe that causes it to pop earlier?

Hmmm, IDK. Maybe I'll unscrew what's in there and install a 145psi blow off valve.

 

[Buddy]

Hmmm, I wonder what the he'll is going on then? Could the compressor be building 400psi inside itself before the regulated side disengages the clutch at 120psi?

I suppose it's possible if the volume output is greater than the flow rate of the most restrictive fitting in your setup. Especially if it's running for an extended period of time. Does the valve reset once it's blown or is it like a valve on pressure tank that once it's blown it's blown?

 

[fishEH]

I suppose it's possible if the volume output is greater than the flow rate of the most restrictive fitting in your setup. Especially if it's running for an extended period of time. Does the valve reset once it's blown or is it like a valve on pressure tank that once it's blown it's blown?

I can't see any way to reset it. Everytime I kick the compressor on it blows. I think I'm going to remove the regulator prior to the pressure switch, the more I think about it I don't think I need it anyways.