Engine Size: 4 cyl
Refrigerant Type: 406
Ambient Temp: 95
Pressure Low: 22-28
Pressure High: 245
Country of Origin: United States
I brought this AC system back to life years ago with R12 thanks to the help from this forum. I had flushed it real good, replaced the expansion valve and accumulator, put mineral oil in it and R12 and was getting vent temps in the 30's. This lasted for months - year (I forget exactly how long, but it was for a good while). I don't drive it that often, but one day the compressor didn't cut on. Since I have other cars I let it sit for a while, but when I started working on it I realized there wasn't any or very little refrigerant in the system. I pulled a vacuum and it has a very slow leak, about 1 psi per day that I can't find so I added about 1/2 oz of dye and about 1/2 oz of mineral oil, pulled another vacuum and added the 406. Since it's a Keihn compressor, I was told that it can't be converted to 134 so my plan is to run the 406 for a while and hopefully find the slow leak, fix it and put R12 back in it. The problem is, after adding the 406 I'm only getting vent temps of 69 degrees at 2K rpm. The site glass is still very cloudy and the evap drain is dripping steady, but of course, not very cold. The compressor never cycles off and once I shut it down, pressures stabilize at 118 psi. Should I still add more 406 to get better vent temps and if so, how much or ??? Thanks in advance!
From the autofrost.com website:
Blends should be outlawed, period, but sure outlawed around here. R-406A is 55% R-22, 41% R-142b, and 4% isobutane. Just one minor leak will release the isobutane, pressures will skyrocket and you will blow your system. You have a dual function switch to prevent that, but it will be fooled. You are only talking about a couple of cans of R-12, find your leak, fix it, and return back to R-12. These cars never converted well to R-134a, can't get a clear sight glass without exceeding pressures. Unless you are willing to make some major changes.
It'd be better to use a sniffer to look for the leak rather than try to run a leaky system with the wrong refrigerant. Put in a small static charge of any detectable gas, R-406 is fine or even R-134a, and don't run the compressor.
Since I already have the 406 in it I'll do the sniffer test in the morning. I'll start with the vents and just turn the fan motor on to see if it goes nuts(EV area), then check the compressor area and start going over everything else again.
For my own knowledge, don't the pressure readings I have show that it should be cooling a lot better than vent temps in the upper 60s?
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