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A/C Compressor Retrofit & Upgrade

  • Model & Year: 84-91 3-Series
  • Expertise: Advanced
  • Date: March 9, 2002
  • Updated:
  • Time Estimate: 10-12 hours

Tools Required

  • Metric tools

Facilities Needed

  • Garage or level surface

Parts Required

  • Compressor retrofit kit

Getting Started

If your E30's air conditioner has gone out (again), I highly recommend converting to the "new" refrigerant, R-134a, and replacing your compressor with a much more affordable after-market type. Stock compressors cost about $800, rebuilding your old one will cost $400, and R-12 Freon is getting more expensive all the time.

At the time of this writing, conversion kits are available and should improve the resale value of your car:

Seltec compressor: $275
Mounting kit: $110
Dryer bottle: $48
TOTAL: $433 + shipping

The kit includes all: a new Seltec compressor, mounting bracket, belt, fittings and o-rings.

My results were great: the compressor ran much more quietly than my stock unit, producing an average temperature differential of a little over 30 degrees at the vent - the same as before. Utilize the services of your local a/c shop for hose work, and let your favorite tune-up shop do the evacuation and re-charging.


I have included the instructions that came with my kit below. They were a little lacking, so I made notes shown in red. Have your car's a/c system evacuated before beginning.

On cars with oil coolers (318is and 325is), you'll need to be mindful of where you route the hoses since there's not a lot of room. I improvised by routing my hoses between the oil lines while routing the high pressure hose toward the front of the car after re-positioning the front oil line. See photo below:

E30 compressor

The low pressure hose needs to be removed and remade to correct length using the provided fitting with new thread size. Utilize your local a/c shop for this: about $10.00. The high pressure hose can utilize the existing fitting.

Once it's all back in, go to a local shop to evacuate and recharge with R-134a. I had them also install the dryer. My total cost for this service: $159.45.

installation diagram
installation instructions
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Texas, USA