2 months ago I had a shop rebuild the high pressure hose connected to the compressor on my 1993 Mazda Protégé, SOHC, 1.8l. They recharged it with something called freeze 12. It worked fine but made a noise it never made before, but only on idle after warm-up. The noise seems to be coming from the compressor and it sounds like a cross between a stuck relay clicking open and closed and the sound made by a playing card being rubbed by the spokes of a turning bike wheel. This noise stops at rpms above idle.

My first thought was that these guys forgot to put oil in it. I took it back and they said the machine does it automatically and there is no way they could forget to do it. Do such machines exist?

They said the compressor was on its last legs and it was a coincidence (the recharge and compressor failure). Now, the compressor seems to be more of a drag on the engine than before. The car shudders as it cycles while diving which it never did before. If the ac is left on, the belt will squeal for a few seconds when the car is first started in the morning. The belt is fairly new, clean and tight. Are these symptoms of a doomed compressor?

Finally, I keep thinking about oil and coincidences. I put the compressor on 4 years ago and added mineral oil per instructions and charged it with R-12. Is it possible that freeze-12 and mineral oil are incompatible? What oil other than mineral oil might they have added and could that be incompatible?

 

Squeling of the belt seems to be a sypmtom of a bad AC pulley, in which case, the compressor needs to be replaced. Most of these refrigerants have oil already in the mixture.

You would have a tough time convincing any mechanic that what they did directly caused a failure in a 15 yr old compressor.

 

Freeze 12 Technically is a "Drop In " replacement for r-12.

It does operate at slightly different pressures, so it can cause something similar to "SPARK KNOCK" in an engine, to happen inside your compressor...

Yes..The Charging stations come equipped with an Oil charge function.....BUT.. I have never ...and will never..put a Compressor on "DRY"....There is a card with the compressor with required oil precharge amount.....

1993-----Why wasnt a retrofit to R134a Disscussed with the tech.....Why Not 4 years ago when you put the compressor on?....

Only some of the "Reputation" problems with R134a actually exist.... It does take a Bit longer to cool, if you consider 30 extra seconds a Problem...But it is every bit as cold and efficient as R-12 ..Provided the system is properly serviced and Maintained...

 

why was the hose replaced? If it had leaked, that means the pressure was low in the system and now, with a fully charged system, the strain may simply be noticable on the compressor

see above

see above plus you may have an engine problem as much or more than an AC problem. I have driven many 4 cyl cars that had noticable engine vibration when the AC was running.

could be several things including a compressor taking a dump.


maybe, maybe not

I spent a bit o timeresearching this before posting. It appears mineral oil is fine.

You would have to ask them. 134a does use a different type of oil.

an overcharged system. If there is too much refrigerant in the system, the compressor is trying to start under a higher load due to the greater pressure from the overcharge. Something to look in to.

If they put in too much oil, that could cause similar problems as well. It could cause an accumulation of oil in the compressor which could simply kill it.

 

I'm no expert on ac systems but about 4 yrs ago I replaced the condensor on my jeep and the system was charged with freeze 12 and still works great. That was cheaper than having the compressor retro'd for r-134

 

just a few things about "drop in" refrigerants. as uncle diesel mentioned in a previous post, FR-12 is a drop in...there are several and they are legal to use. there are many refrigerants in the world...some are for commercial use, some industrial and some are mobile (made for cars and trucks). these refrigerants are approved for certain uses and you can find a list here http://www.epa.gov/Ozone/title6/609/ as well as the regulations that apply to them (refrigerant). drop ins are marketed as economic alternatives (as Mark has already testified) but each refrigerant requires dedicated fittings and equipment for recovery and recharging. I know of no one in my area that sells or services systems with a drop in...so...if Mark moved here to the shenandoah valley and needed service, he'd be out of luck. likewise, if the only place that services FR-12 systems where he now lives went out of business, he'd be out of luck.

i'm neither recommending nor condoning any refrigerant, just trying to spread a few facts sos folks can make informed decisions.

one other note that might interest you...we're not too far from the next revolution in mobile climate control systems...CO2 as the refrigerant gas. no more rubber hoses as CO2 will operate at VERY high pressures...but is MUCH more environmentally friendly...progress is a great thing, huh?

 

uncle d:

I put r-12 in, because I had it at the time. When the hose was replace the shop said f-12 worked better with the existing condenser. Is there no "spark-knock" w/ r-134?

 

nap:

overcharge is something I thought about. The only gauge I have is cheap gauge for low pressure side like a tire gauge. It read 27 psi @ 2000 rpm with the air temp about 80 and ac on max. I don't trust the gauge and have no chart for this car and f-12.

I seem to remember from the old days the the evaporator inlet and outlet should be about the same temp at the fire wall with a correct charge, so I checked that yesterday. With the outside temp about 95, the inlet (thin pipe) felt warm and the oulet (fat pipe) was cold but had no frost or condensation. If what I remenber is true this is an incorrect charge, but I don't know if it means over or under charged.

 

I think you may have misinterpreted my example...

As we know from "Physics 101" ..you cannot compress a liquid. In a normally operating A/C system, what is drawn into a compressor thru the low side port is a Vapor. Unapproved freon, which condenses and evaporates at different pressures and temperatures than R-12, could concievably be in a liquid state when it enters the compressor, Causing a "Detonation" effect inside the compressor. It is possible that freeze 12 works "Just on the edge" of your vehicles pressure capabilities.

Now...before I start sounding like an "Activist" against drop-in FR12.......

I have seen several vehicles react this way with R134a, and 2 of them experienced catastrophic compressor failure, even after my best diligence at a retrofit. Some cars just want R12 and wont accept anything else, although the MFR's tell us it is perfectly acceptable.

 

that is what I have been taught as liquid slugging. You are trying to compress a medium that is liquid with a gas pump.

peabees. with a low side or 27 psi, I would think it is not an overcharge problem. That is far from overcharged.


as to the in and out of the evap; it should be warm (to sometimes hot) on the in side and cold on the out side.

That is because the "in" side is a presurized fluid that has just passed through the condensor. The condensor does not remove all the heat in the refrigerant. What the evap coil does is provide an area for the high pressure fluid to pass through an orifice and expand. That makes it cold and it absorbs the heat in the air that passes over the coil. It is still cold when it leaves the evap coil relative to anything else so your temp feel is normal and correct.

Not sure I would expect any frost on the evap outlet pipe with an ambient temp of 95ş. It should get wet though.