A/C Work

[mbzjag8090]

Hi, I've got a new receiver/drier, expansion valve and evaporator I'm installing in my 84 300SD.

First question:

The compressor works but is 8-10 years old. Should I replace it, too? Consider I am replacing receiver/drier now.

Second question:

Does 134 work well, even in hot climates like TX? When the system was previously working it worked really well even in 100 degree weather with 134. After this investment should I put R12 in it? Mechanic said it would be silly to do so because lines are set up for 134 and he said R12 is so expensive that if there is a leak in any of the work performed it will be easy to run through loads more money.

If you vote for R12, where can I get it? He does not have any.

Third question:

I've got the two A/C lines open with the airbox out of the dash. They were previously attached to the expansion valve. Someone warned me that a couple of days with the lines disconnected would ruin the entire system. Others have said not to worry, even for a week. Right now I've got fabric clipped to the ends of the expansion valve lines. What is your vote...would it be bad to leave those lines open for a week or so.

Thanks very much

[benfield4]

Hi

In July I did a bunch of A/C work to my 89 300SE. Its a W126 similar to yours.

I am not an expert on AC but will give you some of my experiences.

I purchased the car without working AC and put it back to an R12 system. It works great in Washington State! It was more money for the refrigerant but many on here say that 134 does not work well. I never tried it so I can only speak from the R12 side of the fence.

As to your questions:

1. The compressor works but is 8-10 years old. Should I replace it, too? Consider I am replacing receiver/drier now. - You might consider it but if you go the 134 route you have less to loose if you have to evac and recharge it later. I had no idea when mine last functioned so I replaced it. It was expensive.

2. Does 134 work well... - I cant tell you from experience but if you search on this site long enough and filter out all the "Junk Refrigerant" threads I did not get a good feeling for 134. To me it was tempting from the cost aspect. My r12 was $60 a pound and needed 3 pounds so you do the math! Even though i complain of the cost it works well and I am satisfied with it. Your AC man can get it or you can get certified online with the EPA and get it on your own! Cost varies. Check ebay. Search on this site for EPA certification.

3. I've got the two A/C lines open... - I had mine open for 2 weeks with no adverse effects. I replaced all the orings in the system and a new expansion valve, receiver dryer and flushed the whole system. I used the expensive flush compound from Napa. I think it depends on how well you get it sealed and how long you put a vacuum on if for. I bought the $100 vacuum pump from Harbor Freight and a used set of AC gauges. I put a vacuum on it for over 4 hours. I did that before I installed the receiver dryer (Note that I used a fitting where the receiver dryer was). I then opened the system again to install the receiver dryer and then put it under a vacuum for another 4 hours. The next day I drove it to my indi mechanic for a charge. Has worked fine since! YMMV!


There is a lot of info on this site. Search and read my friend! I guess I went the purist route and made mine stock. I think my AC in the car works better than the 134 system in my 01 F150 and even my wife's 05 Honda CRV. Not sure how old you are but when I was a little kid I remember freezing my butt off in the front seat of the family car which was a 72 Chevrolet Caprice and that was R12.

BTW how was that expansion valve on your car? That's a bad spot for something to work on with fittings!

[mbzjag8090]

Thanks for your thoughts benfield4. I'm rebuilding the airbox while I'm at it so have replaced the evaporator and expansion valve. I agree it would be very tough to get the expansion valve off the evaporator fittings with the evaporator in the car. They were really tight. Since the whole airbox is apart I was able to leave the upper fittings attached since a new unit is going in.

As it turned out I needed to check the position of the o-rings so with the evaporator out of the car I let the upper expansion valve fittings soak in some catalyst (like WD-40) which made them easier, but still extremely difficult, to remove.