Automotive Air Conditioning Information Forum (Archives)

fortee9er on Mon July 23, 2012 12:22 AM

Year: 1984
Make: BMW
Model: 745i
Engine Size: 3.5
Refrigerant Type: Feeze12
Country of Origin: Germany

My 1984 BMW a/c has never beed close to adequate. It cools the air but never ever puts out cold air. I understand that this typical for German cars of the period. I want to know if there is anyway to get it to actually perform like an American car or newer cars. What would it entail? replacing the compressor, evap. condensers, hoses...? I would appreciate your comments and suggestions.

bohica2xo on Mon July 23, 2012 3:26 AM

I recall that the 7 series of that vintage had a decent multi-path tube & fin evaporator arrangement. So as long as the evaporator housing seals right & the fan is working well, that part of things should be ok.

The condensor is the most important part of the system. You would need to replace the OEM part with the largest parallel flow unit that you can fit in the car. Next on the list would be making sure it has adequate air flow at low speeds. The fan clutch & fan need to be working, all shrouds in place. No air can bypass the condensor on the way to the radiator & fan assembly.

Finally, that would have been a wing cell compressor if it is factory A/C. Not the greatest unit to start with. It would take some bracket fabrication to put a different compressor on it. Something like This V5 compressor would be a good choice if you have the ability to fabricate the mounts.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

fortee9er on Thu July 26, 2012 2:33 PM

fortee9er on Thu July 26, 2012 2:36 PM

Pardon my ignorance but why a GM V5 compressor. I don't know anything about it but whenever I hear about a/c updates it is always in reference to a Sanden or another Asian brand whose name escapes me at the moment. I don't have any favorites here just want good reliable cooling power.

atikovi on Thu July 26, 2012 8:33 PM

Your 745i is a grey market model that was never sold in the USA. Factory BMW A/C of that period will blow ice cold. The importer probably installed a universal A/C kit which is why its output is marginal.

bohica2xo on Thu July 26, 2012 8:58 PM

49'er:

The V5 is a good solid variable displacement compressor that can compensate for the evaporator in that car over a wide variety of conditions. It also handles high rpm operation well.

Euro cars that vintage blow "ice cold"? HAHAHAHA maybe at 75f ambient & 200kph on the autobahn.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

fortee9er on Thu July 26, 2012 10:52 PM

Are there any markings on the V5 or which cars/trucks did GM put them in. I was thinking of going to the junkyard and getting one to see how it will fit and what brackets will need to be made.
Can someone make a paralell flow condense to the same dimensions as the stock unit with the fittings in the same place as the stock unit?
BTW I have an 1986 Volvo 760 turbo that haas been converted to R134 and it does better than the BMW but it still barely adequate. The BMW does better when it is in a covered parking space/garage not left out in the sun. If left out in the sun it takes forever to cool specially since it is black on black. The Volvo is white with cloth interior so it cools down quicker.

bohica2xo on Thu July 26, 2012 11:40 PM

The V5 & the V7 were used in several GM lines. The V7 has more displacement than the V5. The reason I used that link is that it shows the V belt drive pulley. The V belt pulley will fit on any of the V5 /V7 compressors.

V5 / V7 units have been made with both ear mounts like that one, and pad or crossbolt mounts like This.

Corvette & Camaro around the 2000 model year had a pad mount V7 Ear mount V7's came in things like the 1998 to 2003 S10. That V belt V5 is from a1986 Cavalier. Ear mount V5's were in many GM cars 1988 to 2003 A 1996 Lumina 3.1L would have a pad mount V5 with a serpentine clutch...

Lots of choices.

As far as condensor choices, you will be doing custom plumbing with a universal PF unit. Even if you find an OEM unit with the fittings in the right area the hose ends will be different. What sort of space do you have for the condensor?

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

Olds442 on Sun July 29, 2012 2:57 AM

Why was the Volvo converted to 134 ? That was a mistake. Change back to R-12, it cools much better.