WARNING! Do not attempt to repair the AC system if you are NOT a licensed technician with R12 qualifications! Can be hazardous and illegal!
Since extracting a broken AC compressor bolt, my AC system has been evacuated and with the Florida summer temps rising I knew I needed to get to work on recharging AC system. My 944 was still running an R12 system and until the broken compressor bolt incident (requiring removal of the compressor to extract the bolt, thus evacuating any R12) my A/C worked and was blowing semi-cold, though I feel it could have been better.
After weighing both R12 and conversion R134a options, I decided to stick with R12. Here is the cost breakdown to recharge:
- R12 (two cans via eBay): $70
- Oil Charge: $10
- R12 gauges (eBay): $23
- Side can tap: $9 (recommended as many old stock R12 can tops can be rusty)
- Vac Pump: $18 (Harbor Freight, requires air compressor) Somebody sells this model on eBay for twice as much so avoid overpaying.
So for around $130 I could have working AC again. My compressor/drier was replaced a few years back with new O-rings (previous owner). I would probably look into replacing the compressor and definitely the drier and o-rings if you are considering an R134a conversion. I was quoted $160 for R134a recharge only and I would have to install all the conversion connectors and changeover drier myself. I was also worried my 27+ year old system would hold R12 fine but may leak with R134a even with new o-rings.
Here are the steps I followed:
- Connect gauges. The high side connector is by shock tower.
- On 944 years 87+, Low side connector is on compressor. (turn the steering wheel left, and you should be able to access it through wheel well without jacking up car)
- Pull a VAC for 5 minutes, check for leaks/see if it holds VAC, then VAC for 30 minutes or longer to draw out moisture. (both high/Low Side Open)
- Close high/low side valves, remove vac pump, connect Oil charge to yellow service line.
- Purge the service line of air (this is done by unscrewing the top of line at the gauge manifold slowly until oil/freon bleeds out slightly. Do this prior to each can charge to prevent pumping air into the system.
- Start engine, turn AC on low temp and high fan.
- Open only the low side valve and oil/R12 charge will be drawn into system.
- Repeat steps for next 2 cans (check sight glass to see R12 flowing into system)
- I chose two 14oz cans + 2oz with oil charge can for a total of 30 oz R12. My compressor had residual oil you may need more oil if new compressor.
Temperature 42 degrees at center vent with fan on 2 setting on a 90 degree Florida day. Success!
CORY ON CARS 