Residential R-22 system. HO added 134a

[Magnapro]

I am the stupid homeowner that added R134a.

15 years ago I was a certified Automotive and Diesel Mechanic with additional certification in A/C and Electrical repair. I broke my back in 1995 and forced career change, so no longer certified.

I have 20 year old 2 1/2 ton spit system in my home (Bryant). The system has never given me a bit of problem other than needing a little added refrigerant every 5 years or so.

Last year I put my gauges on and saw that it was time for more refrigerant. I had used up all my R22 on previous service.

Since I am no longer certified, I could not buy any R22 or so I assumed. I did not even think is was available any more (I had confused rumors I heard of R22 Equipment Ban with R22 Ban). So the only thing at hand was R134A and the can said it was compatible with all R12 and R22 systems. (12oz automotive cans, some with POE oil included) I added I think 2or3 12oz cans with or without oil. I am not sure how many cans had oil, but those that did I believe are 10oz of R134A and 2 or 3oz POE oil. All I could find on a Sunday when I had time to work on my system. The system did not get as cold as I thought it should, but I lived with it for remainder of 2009 season.

This year when I tried system for first time I was getting about 65F air out of vents. I again added 2 12oz cans of automotive R134A (no oil). Did not change temp by more than a couple of degrees. A-coil was only getting cold about the bottom 5 inches. Acted as though still low on Refrigerant.

Then I did what I should have done last year, I researched differences in refrigerants and found.
1. R134A only produces about 65% of cooling compared to R22
2. POE oil and MO do not mix
3. R22 is still readily available.

I am not sure how much, but I have to assume that I added 3-6oz of POE oil to my system as many of the automotive cans include this by default. I can not afford to replace entire A/C system at this time and pressures are still good and compressor sounds good. I have evacuated system to 25" vacuum for 6 hours and have ordered R22 to refill system that I should have delivered some time today.

So my question: Everyone talks about how detrimental MO is to R134A and POE system. But what can I expect from POE contamination of my refilled R22 MO system?

my system is:
Year 1989:
I Live in SE Michigan, USA
bryant model 591A030 Condensing Unit
bryant model 507J 030 A-Coil
15ft - 18ft 3/4" Vapor Tube & 3/8" Liquid Tube

Thanks in advance for any advice you may have,
Sincerely, Fred

[monkey spanners]

Hi Fred,

If the oil you have added is poe that is to say polyolester oil then it should mix ok with mineral oil. I don't know what viscosity you added though, i would expect your R22 comp to be on a 3GS type oil whereas most old car ac would use 5GS so maybe the oil you added will be a bit thicker than needed.
It is PAG oil and mineral oil that don't mix well. PAG oil is whats in all new R134a car ac systems.

Why have you only vacuumed to 25" and not 29"?
Why not just fix the leak and save all this topping up hastle?

Jon

[Magnapro]

Jon,

Your right, my mistake it is PAG oil that is in the R134A I added. That is what I was concerned with mixing with existing oil in my R22 System. I have had vacuum pump on system for about 10 hrs now at 28" vacuum. most of what I have read says that is the best at removing oil is deep vacuum. I'm going to charge it tonight and hope for the best.

Fred

[Magnapro]

I cant' see anyway to edit post.

sorry I forgot to reply to your question about leak.

I have never seen any sign of a leak. it takes 5 years for refrigerant level to drop enough for me to notice a difference in system operation. I guessed the vacuum level when I posted first post. upon looking at my gauge later I saw that it was really 28-29'" vacuum. I did not run vacuum pump overnight, did not want to disturb neighbors. But before I turned pump back on about noon today gauge still showed 28" vacuum. I believe that in itself shows that if there is a leak it is tiny. I'm actually surprised it held vacuum for over 15hrs since i did not close service valves and that means my pump and gauges also held.

Fred

[Magnapro]

I have searched the internet far and wide to see if anyone had anything to say about adding Automotive R134A to R22 Residential Split System. I know I screwed up, acted first and investigated after.

I never found anything conclusive about PAG oil contamination of my R22 system, everyone talks about the other way around. MO contamination of R134A system.

Everything I read about flushing (many problems in itself and chemicals involved), drilling hole in hermetically sealed compressor to drain oil and change oil sounded too extreme. Especially with no good data one way or the other about effects of any left over pga oil. at least not that I could find. The R134A and PGA oil has been mixed in with R22 and MO most of last season. No noticeable ill effects that I can see.

I have now evacuated at 29" for about 18 hours and recharged back to R22.

System is running perfect and superheat numbers match manufactures chart.

Outside Dry Bulb: 78F
Outside suction temp at condenser unit: 59
Suction Pressure: 70 PSI (41F Sat. Temp)
Liquid Pressure: 235 PSI
Inside Dry Bulb @ intake of evap: 78F
Inside Wet Bulb @ intake of evap: 65F
Manufacturer Superheat Charging table calls for SH of 18 at these temps/press.
1989 bryant 2 1/2ton spit system 591A030

I guess I am just going to cross my fingers and hope that introduction of R134a and PGA oil were taken care of by deep vacuum and will not cause compressor failure. Hell I have already got 22 years out of this unit and it still runs like the day it was installed. If it fails, I'll bite the bullet and have entire new system installed.

Thanks for all the help, Mostly from many pages of reading on this forum.

Fred

[monkey spanners]

Pleased you got it working again!

Jon