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Hi,
Finally got around to fixing my AC. It's been on R134 for many years but I had a leak a while back and finally decided to renew it all.
- The system itself had a ton of UV dye, ester oil, and other crap from over the years. Flush flush flush. I wanted to go to PAG100 anyway, so it was doubly important.
- I rebuilt my seiko-seiki compressor (SS170PSS) and used PAG100 per the spec for 134.
- when rebuilding the compressor - those aluminum washers on the 'head' bolts do not reuse well. Get a copper washer set from the autostore and replace with like sized copper ones.
- I bench tested the compressor for leaks and for pressure.
- You need to spin the vane types with a drill or better, a v-belt from a motor to get it to work. Twisting a vane type by hand will NOT generate pressure as theres not enough centrifugal force to get the vanes to push against the wall of the cylinder. I probably threw a way a few compressors in the past thinking that they weren't working.
- I replaced the clutch bearing (40x62x24mm btw).
- I flushed my system thoroughly (condensor and evap and lines). I used denatured alcohol and compressed air flushed both ways a bunch of times. I also did full charge up, ran it for a bit, and then reflushed. even more crap came out.
- I replaced the drier and the expansion valve.
- I pulled a vacuum for 30 minutes
- I replaced all orings, and my valves. There's a useful Sanden kit for Porsche that contains basically everything. Orings, valves, caps, and so forth.
- I charged it with R134 based off of pressure readings. Multiple sources indicate that sight glass is less than useful for R134 systems.
- At 90 degrees outside, I had 30-40 low side pressure, and on the high side had ~240-250 PSI at ~2000 RPM.
- I used a digital laser thermometer to measure a 50+ degree drop between the inlet port and the outlet port on the condenser. That probably was reduced as the whole car heatsoaked.
- I have non-oem slimline fans that my guess is don't work as well as the OEM, but they're dead silent and are more than enough for the radiator only. They both operate as expected, but I think that they may not get enough airflow over the condenser at dead stop in 90 degree heat. This is probably why my head pressure is a bit high.
- Back of the hand I use is temp*2+50. so 90 * 2 + 50 ~ 230PSI. BTW, these were 20 bucks on amazon a pop and are way quieter and draw way less power than the old OEM ones. I don't even notice they're running. It's been 90-100 and I sit in traffic and my temps are very stable. Plus they give you a lot more room between the fans and the engine.
Several "issues".
1. After about 3-4 minutes and reading 60-70 degrees at the cold air vent, my compressor cycles off. I believe this is the Anti-Frost switch kicking on too early. I have heard of a few things. Firstly, just to test the switch, which I will do. Secondly, there are several suggestions in the manual to change the location of the switch's sensor bulb in the condenser. I'll readjust to a warmer spot and see if it'll run longer. Are these switches adjustable themselves? Also should the circuit be open or closed when it reaches the cutoff (32f?)
2. I don't have good head pressure at idle. Around 160. The book indicates that you need to do the charge at 2500 RPM, and several other sources indicate that as well. At 2500 RPM, pressures are, close. Has anyone gotten the correct high pressure at idle, or do these compressors just not put enough at the idle RPM to support real cooling? This would only be a problem sitting dead stopped in traffic, unfortunately I live in an east coast city, so most of the time I am in dead stop traffic.
3. My compressor is slightly noisy. A bit noisier than my other seiko-seiki in my 90 NA - but not too much. Does anyone have a fix for that? After pulling the compressor apart I cleaned everything up, and honed the chamber, sanded/smoothed out the vanes (there was some scoring on the chamber). My guess is it's operating OK but not at peak efficiency, but I don't know why it's noisy. There's no bearings! Thought about sticking some thin rubber bushings between the compressor.
4. I know I know, but it feels like a drag when I run with AC on. I have a new IAC which has helped the problem significantly (at idle it no longer wants to die after dropping from ~2K rpm) but is there anything else one can do to make the AC experience more enjoyable? I'd think a slightly higher Idle RPM would be ideal.
5. I put in about 18OZ (a can and a half?) of refrigerant, but I went by pressure, not by the weight FWIW.
Okay, that's it for now! Just thought I'd do a write up and ask a few questions. I also attached a compressor diagram just for the archives.
posted by 98.114.12...
SEIKO-SEIKI-SS170PSS-DIAGRAM-PARTS-NUMBERS.pdf
1
, Fri, 15 Jul 2022 11:26:07
, Fri, 15 Jul 2022 19:15:121, Fri, 15 Jul 2022 08:06:28
, Thu, 14 Jul 2022 18:58:52, Fri, 15 Jul 2022 06:07:33
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