So here is my plan and I hope that someone with more experience than me would chime in and tell me if I'm not getting something right
- Sort out electrical issues first. As I understand the blower should turn on no matter what's going on with refrigerant level or compressor. Possible candidates here are blower relay, switches, wiring or just dead blower motor. Looking at pictures online I'm thinking that heater blower motor and AC one are different, am I right? Just thinking ahead if I have to get a new one.
- Once I have the fan running I also want to check if compressor clutch is getting a signal to turn on. I suppose that with jumping the pressure sensor and unplugging wire to clutch (I don't want to run compressor on empty system) I should see 12V on that bullet connector?
- Not sure if there are any vacuum actuators on the AC duct, but I'll check that as well
- I'm pretty sure that system is empty of refrigerant after few years with hoses that look pretty dry-rotten. I can think of couple ways to check that like checking if pressure sensor is closed or open or actually checking the pressure on one of the service ports with a gauge
- Original system is R12 and I think my best option is to convert to R134a - hoses look like they need replacing anyway, R12 is pricey on eBay and R12 "alternatives" are all flammable gases that I don't want anywhere near engine or passenger compartment. More questions about conversion below.
- Once I fix the electrical issues, convert the system to R134a and recharge it I should be good, right?
- new hoses - mostly because old ones are probably leaking like a sieve anyway. Saw a lot of folks suggesting getting barrier hoses
- o-rings and other seals - once again, old ones are old and I'll need new ones that are R134 compatible
- drier - need new one since desiccant is refrigerant specific and I also read that it's a good practice to replace that if system was open
- oil purge - have to get all mineral oil out before introducing R134 to the system. Some say that just pulling a vacuum for hour or two is enough, some suggest using nitrogen or some special flushing solutions
- expansion valve - not sure if original is R12-only, but it's not crazy expensive and easy to get
- condenser - some mentioned that because R134 is less efficient as a refrigerant than R12, replacing stock finned condenser with parallel flow one is a good idea. I never had a vehicle with R12 AC, so I don't know how cold it is compared to modern ones, but I want cold Also not sure whether new condenser with fit with stock transmission cooler if I go with ebay kit (linked below)
- compressor - as my rig is 88 it came with York compressor (no idea about it's condition though). I've read that later years Sanden compressors are more efficient and more R134-friendly (Yorks supposedly are prone to blowing front seal after conversion). Is that so? Should I upgrade to Sanden or leave York?