PeachParts Mercedes-Benz Forum - View Single Post

James L · #5 05-11-2007, 10:55 AM

dannym, The oil info I averaged from the info that is all over the map; (as in correct R12 weight 2.1-3.5 lbs) data from the service cd, enclosed R4 instructions, alldata, this site and others; info ranges from 8oz, 6.7 oz (max in service cd), 6 oz, 5.6 oz.

Flush solvent; first used the $15 aerosol a/c flush with hose from advance auto, followed by mineral spirits and lastly brake cleaner, this was followed by alot of shop air to insure all was out. (this was done numerous hours back and forth with drilled out expansion valve and without).

Mineral Oil; BVA 4 is a wax free napthetic mineral oil only for CHCF refrigerants like R12 and R22, it has better flow at 300 visc, used Castrol 500 visc mineral oil (5.6oz) last year and had compressor failure, wanted the best mineral oil I could find.

More background; a/c project was finished about 3 weeks ago. went on interstate 2 hour drive, vent temps were about 58 at 85 ambient. Noticed the expansion valve and low side return hose had ice (looked like dry ice) ETR probe was not pushed in enough (although I do not think this was the cause of the ice). went on driving 3 more hours to the mountains (Asheville) and was getting 38 degree vent temps. I was worried about evaporator freezing so I had to monitor vent temp with probe and switch to high fan, economy or off to get vent temps up.

The expansion valve I used was the $19 APA from ********az. I am starting to think I got a bad one and it may be too open (reason for the high low side), also expansion valve o-rings may not have seated right, who knows. (W126 expansion valve work is such fun back bending work). I may order the $35 German one.

Other thoughts;
1.add a half a can of R12
2.clean evaporator through blower hole for blockage
3.reclaim, recycle, re-vacuum (30 minutes, then hold overnight as dannym said, then a full 4 hour vacuum with heat)
4.reclaim again, new expansion valve, re-vac again.

advise, thoughts please
thanks