Older Accord Not Cooling Well...

PoodleHead on Fri August 06, 2010 12:34 AM

Year: 1987
Make: Honda
Model: Accord
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!

ACProf on Fri August 06, 2010 2:24 AM

From the autofrost.com website:

Quote
ALL BLENDS, INCLUDING AUTOFROST, MUST TO BE CHARGED AS LIQUID to prevent composition
change, and possible damage resulting to the system. Autofrost/R-406A/Chill-it/R-414A cylinders
contain a DIP TUBE that withdraws the product as liquid from the bottom with the cylinder
UPRIGHT. DO NOT turn the cylinder upside down to get liquid!! This will give you vapor
instead. Cylinders are marked with arrows to keep upright for liquid.

R406 is a blend and must be charged as a liquid. This involves some technical "expertise" to avoid slugging the compressor. I've used R-406A in an '85 Suburban dual evap and it worked better (colder - faster) than R-12 and carries the R-12 mineral oil just fine. Unfortunately, it also leaks through the older OEM non-barrier style hoses. By the end of the season it starting to fall off, and it was empty a year later.

NickD on Fri August 06, 2010 8:01 AM

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.

PoodleHead on Fri August 06, 2010 9:52 AM

Quote
Originally posted by: ACProf

R406 is a blend and must be charged as a liquid... Unfortunately, it also leaks through the older OEM non-barrier style hoses. By the end of the season it starting to fall off, and it was empty a year later.

I did charge as a liquid adding a little at a time and watching my pressures... I'm not counting on this for a long term fix, just temporary to find the leak... I was told the gas that carries the mineral oil leaks out first so it can cause damage to the compressor due to lack of lubrication. Adding a couple cans of R12 to find a leak I'm sure is a better way to go, but with limited R12 and the cost of it I decided to use the 406a.

Do the pressures I listed above indicate over/under charge or about right or ?

Thank you!

mk378 on Fri August 06, 2010 11:30 AM

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.

PoodleHead on Fri August 06, 2010 8:31 PM