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Tim-Spruill 07-06-2012 06:08 PM

Won't compress refrigerant
I am confounded by my current a/c problem. Vehicle is a Verde. I have had a/c in this car for several years now. A couple years ago the compressor froze so I replaced it with an old one I had sitting on the shelf. A year later that one froze due to a catastrophic internal failure. This time I decided to get a new compressor so I did not have to do this again the following year. I was able to find a place selling them new in the box. I flushed the system in case there was any debris from the old compressor failures. I removed the expansion valve and verified its functioning and made sure it was clean. I reassembled the system and verified it was dry and clean and would pass compressed air with no blockages. I replaced the receiver/dryer. I made sure the compressor had the correct amount of oil. Once completely sealed I pulled vacuum on the system and verified no leaks. I am listing all these steps just as an FYI to those reading.

Here is where it all goes wrong. I began to charge up the system and nothing happened. The pressure went up on the low side and high side remained 0. The compressor did not come on. I assumed the pressure switch was dead so I checked a spare and installed it and started over. Same results. I then bypassed the pressure switch with a piece of wire and shorted the compressor clutch. Here is where it gets weirder. The compressor ran but the pressures stayed the same. At this point I assumed the compressor was a dud and ran out of time to deal with it.

Fast forward to today. I removed the compressor, tested the rest of the system for flow and tested the compressor for suck and blow. It all passed so I reinstalled the compressor, checked for leaks, pulled vacuum, etc. Before I added any refrigerant this time I decided to test it with plain air. I put about 40psi in the system and the compressor kicked on and the hi and lo sides saw what I would expect as correct pressures for such a low volume of gas. I assumed the problems were solved even though I had no idea what I did to fix it. I sucked out the air and pulled vacuum for a good while to make sure it was all clean and dry. I put a can of refrigerant into the system aaaaaand.... nothing. It is the same story as above. Nothing happend. When I shorted the compressor to run it still did not move any refrigerant.

So my question is.... Why will the compressor move air but not refrigerant? Why does the pressure switch recognize air but not refrigerant? What is fundamentally different between air and refrigerant? I don't get it.


Roadtrip 07-06-2012 06:30 PM

I hate to ask the obvious, but it needs to be at least asked . . . You did puncture the top of the refrigerant can and actually have gas coming out the blue hose, right?? I mean if you left the blue hose unconnected and open the valve, gas comes out?

No problem with the R-134 adapter screwed onto the old R-12 port right? Did you remove the old schrader valve before putting on the R-134 adapter, or did you need to do that? I assume you're using R-134 adapters and hose connectors?

With the ENGINE/COMPRESSOR OFF and the system evacuated, and not taking gas through the blue hose, will the high side take it through the red hose? AGAIN . . . THIS IS NOT NORMAL. DO NOT OPEN THE RED VALVE EVER UNLESS THE COMPRESSOR IS OFF, AND THE SYSTEM COMPLETELY EVACUATED. Just trying to determine if there's a blockage with the low side port or gauge set.

STANDARD WARNING TO ANYONE READING THIS: NORMALLY, DO NOT EVER OPEN THE RED VALVE WITH THE HOSES HOOKED UP. Doing so with high pressure in the system and the refrigerant can hooked-up, WILL explode the can.

Tim-Spruill 07-09-2012 05:54 AM


you ask good questions. Yes, the can is open. I can feed gas into the system. I still have the r12 fittings on the compressor because that is what my gauge set uses. It is old but works well.

I did exactly as you were thinking. After I got no results on the low side, I opened the high side valve to feed in some refrigerant and all I really ended up with is equal pressures on both gauges. The compressor still would not come on and when I shorted it on it would not compress.

Now here is the good and bad news. I friend of a friend who is an a/c guy came over this weekend to help with my troubles. With his help we located two leaks. One under the dash at the evaporator exit fitting and the other at the shaft seal of the compressor. Since the compressor is new I am going to send it back and have them fix it and test it. I will work with my other leak in the mean time. This still does not solve my issue of the compressor not working but it is a step in the right direction.

Just fyi, I am using ES-12 rather than 134a. There have been many threads on here and other forums about it being dangerous. Leave that there, not here. I am huge proponent of that refrigerant for our cars because it is more efficient. On that same note though, my friend did a test charge for leak sniffing and the compressor worked just fine for that. I am wondering if the specific refrigerant makes a difference. I have run es-12 in all my alfas for several years now with no issues. I don't see why it would be different now.


papajam 07-09-2012 06:08 AM

Turn the can of refrigerant upside down. This puts the refrigerant in as a liquid, not a gas.

Roadtrip 07-09-2012 07:28 AM

Tim - Are you installing the ES-12 as a liquid? Like Papajam says. ES-12a is an HC refrigerant and must be installed with the can upside down and as a liquid, unlike R-134a. You should go back and print out the installation instructions from the Enviro-safe website:


4 - Connect gauges and hoses. With compressor off, open cylinder "liquid" valve or invert can to install ENVIRO-SAFE on low pressure side of compressor (installing as a liquid will not harm the compressor). Establish flow. After an initial minimum charge is achieved, start compressor and set system to high. Continue adding ENVIRO-SAFE as needed to achieve either the proper amount as determined by the equivalency ratio or the proper pressure level according to manufacturer's specifications. DO NOT OVERCHARGE! Exceeding 60 psig on the low side may damage compressor. In some cases, clearing the site glass overcharges the unit. Any overcharge may cause loss of cooling efficiency.

I have used ES-12 in an old Jeep R-12 system and found it was inexpensive and worked extremely well.

Tim-Spruill 07-09-2012 07:37 AM

I am using the can upside down. The only instructions I have not followed from their company is regarding vacuuming the system. They say not to start with a vacuum. That makes no sense to me and when I called they said their reasoning was to do with overcharging. They say their system does not interact with moisture in the same as traditional refrigerants and they are correct, but any moisture can freeze if the temps get too low so I believe it is better to suck it out rather than have humid air in there. Technically a properly charged system should not go below 32 but I am not perfect and neither is the system so why chance an ice blockage that can blow out your hoses.

Ironically, I never put more than 60 psi in there when I was trying to charge. Guess I got lucky. I just opened the can and let in what it would take.


Roadtrip 07-09-2012 07:51 AM

Assuming no Expansion or POA valve blockages, I think you're down to a compressor problem. Let us know how it goes when you get a new compressor.

Tim-Spruill 07-09-2012 08:04 AM

Will do. I am going to take the compressor out tonight. Calling the company I purchased it from at lunch today. Hopefully they will take it back and fix the leak or replace it. The 90 day warranty went up last summer when I bought it. I have been too busy to mess with it since then. If they won't do it under warranty I may send it back for work anyways. If they want an arm and a leg I will take it to some place locally and have it done. Quicker return that way.

I will everyone know the results when it is complete. I have a wrecked milano coming later in the month. Might grab the compressor off that car in the mean time.


Joe Papa Sr 07-09-2012 02:47 PM

From last summer, I doubt they will honor a warranty of only 90 days. Way too long ago. But, how much $$ are you thinking to spend on a "new" comp? I have a good source I might look up for you if youd like........

Joe Papa Sr 07-09-2012 02:51 PM

With HC's, I vac down to about 10HG, then add the HC as liquid. This is recomended as compared to R134a or even R12 cuz HC's are not a homogeneous chemical compound. HC's are 2-3 compounds stuffed in a can, and if introduced as gas it will separate and not behave well, but still, not a big deal!

It will eventually mix with some cycling.

Trace water has no effect on ac system with HC's. I wouldnt worry about trace water. Thats what the drier is for- a dryer should absorb up to about 10 milliliters of water.

Tim-Spruill 07-09-2012 02:52 PM

This was a brand new compressor out of the box from Sanden. Paid $209 plus shipping. These guys are really nice out of Texas. "AC Parts" is the company name. Called them up and they said to send it back and they would take a look. I guess we won't talk money until they open it up and test it. If I have to pay I have to pay. Oh well. That is the price for being too busy to take care of things when they happen.

If anyone needs a new compressor that is a sanden and matches the original perfectly, these are the guys to get it from. I had to have them put a used head on it to match the factory fittings but that was it. No charge even.


Tim-Spruill 07-09-2012 02:57 PM

That is good information to have. I am still learning the concepts of a/c systems. I learn quick but have had to teach myself so far. Need to take a class or something.


Joe Papa Sr 07-09-2012 03:01 PM

here is one:
1972-1990 Ford Mazda Renault Saab Dodge AC Compressor | eBay Romeo|Year:1987|Model:Spider&hash

I have bought comps from these guys and believe they are professionals with a decent product. Rebuilt with warranty. Of course, new would be about $210 or so......

mkeith 09-01-2012 10:11 PM

Are you still having problems with this A/C job? Have you tried a different guage set? In your first post, it sounded to me like your blue hose is plugged. It's happened to me more than once. Refrigerant will pass from the yellow hose to the manifold, but it will not get into the system due to the clog. Therefore, although there is nothing getting into the system, the low side gauge will still show pressure.

Tim-Spruill 09-02-2012 11:08 AM

The current status of the project is that I have a leak to fix and am waiting on the compressor to come back from the folks I got it from. I ended up finding a friend of a friend who was an actual ac guy. He came over and looked into it. You might be right. When he put some 134a in the system it worked great. But he brought a sniffer and we located a leak and also a potential problem with the new compressor. I called up my supplier and they agreed to take it back and inspect it. Latest is that they are changing the clutch and leak checking the whole thing. I called them a couple days ago and they did not have any answers for me. Then we had a storm. I need to call them back.


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