Changing out A/C compressor


1994 Chevy K1500 Blazer, 223K miles

The A/C compressor has holes rusted into the casing; any refrigerant bubbles its way out in a matter of days. I’d like to replace it, but I want to confirm the steps of doing so.

1. Have system evacuated (not needed in this case - all charge has leaked out)

2. Replace receiver/drier and expansion valve/orifice tube along with the compressor

2a. Replace any o-rings where lines were disconnected

3. Have the system flushed, vacuumed, and recharged by a shop

Am I missing anything, or is this pretty much it? And one other thing: where the heck is the expansion valve/orifice tube located? It’s not listed in my Haynes manual, and I can’t seem to find it by looking under the hood along the A/C lines. Is it buried in the dash near the evaporator, or somewhere else?


The orifice tubes are usually located in the high pressure lines between the condenser and evaporator. On your model I think? it’s located at the high pressure hose/evaporator connection. They usually require a small special tool to remove and install them, although sometimes a tiny pair of needlenose may work.

It sounds like you’ve got it covered, but if it were me I would go ahead and replace every O-ring in the system. O-rings are cheap (comparatively anyway) and you would hate to spend the bucks having the system evacuated and recharged just to develop a leak a few minutes later; or a week or so later.


Sounds like you’ve got it. Do the mechanical work yourself, but let the experts (an automotive AC shop) finish the job.


A bit of an update-

Today I was doing some hunting for the orifice tube (which I still haven’t been able to find). Internet research has said it’s in three possible places: right behind the passenger-side turn signal on the condenser outlet line, right at the evaporator inlet line just inside the firewall, or along the same line somewhere inbetween. There should be dimples in the line where it’s at.

So I decided to check behind the turn signal next to the condenser. Unbolt the line and start sliding the hose out…PSSSSSSHHHH. I guess somehow there’s still refrigerant in the system, and it didn’t all leak out like I thought. So an evacuation will need to be done before I go further.

Also, a neighbor walked up and said that the orifice tube is just behind the firewall under the receiver/drier, and that removing the liquid line there will allow you to pull the orifice tube straight out through the firewall. How does this sound to anyone? I had hoped it wouldn’t be this difficult to find the stinking thing…



The expansion valve is a orifice tube located in-line between the receiver/drier and the evaporator. There should be a connection at the firewall and the orifice tube is located there.

STAR, GM hasn’t used a expansion valve with a capillary tube in some time. They use a orifice tube. You wouldn’t know this because you have no automotive A/C experience.