R134a -> R12 un-conversion
 

So...Last summer I rebuilt my AC system (thanks to all who helped), but didn't get it finished until fall when the temperatures had already dropped. I went through the entire system and did it "right" (except that I used r134a)

Parallel flow condenser (oversized, I think 16x24")
Sanden compressor
All new hoses
New drier
New evaporator
Oversized (16" I think) modern cooling fan
Rebuilt climate control switch assembly
New sensors all around
Every single component of the system minus the blower motor was replaced.

Anyway, as predicted, it's not working as well as I'd like. On 80 deg days, driving in traffic, the system is blowing barely cool air (Yes, I need to measure the actual temperatures, but lets say they are inadequate for my comfort level), once I get to the highway it's usually pretty comfortable. I think the compressor and fan are running pretty much non-stop.

Part of this seems to be that the blower motor is pretty wimpy, so even when it is running on max, I'm not getting a huge volume of air. I'm not sure if this is normal for these cars, or not. It may be worth trying to rebuild the blower motor, or sourcing a new one.

I also did a quick test this weekend, idling in a parking lot after a fairly long drive I popped the hood and felt the condenser. The fan was running, but both the input and output side of the condenser were pretty warm to the touch. I'm not sure what the expected operating temperatures are for this, but it seemed warmer than I'd expect.

My plan is to take it into the shop that did the charge last year and have them hook it up to their machine again and ensure that I'm at the proper operating pressures. I'd do this myself, but I trust their equipment more than mine. If it's not a problem with the charge, my next thought is to try to improve the cooling capacity at the condenser, possibly by switching to a dual fan system (I'll need to modify the bars that link the radiator support to the frame behind the bumper)

If this doesn't work, and the system checks out that it's operating normally, I'm considering converting back to r12. Obviously I'll need to find a shop with the proper equipment, or get the license myself, as well as try to source some old stock r12. What else is required to convert back? Obviously a new receiver drier, and probably a new condenser as PF condensers can't be flushed properly. Is it safe to reuse the compressor? I'd really rather not spend the money on yet another one.

Thanks, and sorry for the wordy post.

Consider R152A (canned air duster). It is reputed to work nearly as well as R12 and is a fraction of the cost. It has the added benefit that it is compatible with PAG and POE oils used in modern refrigeration systems so you don't need to do a flush. Another member posted recently about converting to R152A and had nothing but good things to say about it.

Ahahaha. Okay - so I just called the shop that did the charge on the system before:
"Well, we don't work on German cars, if we did before it's because we did you a favor, there's just not enough demand, we don't have the special tools, but we do work on Japanese stuff"
...
So apparently those special tools are "wrenches"? We're talking a 30+ year old car here, the only special tools I've ever bought for it were spring compressors...
...
Called a different shop that's worked on it in the past too, they're happy to take a look at it :)

(I've messed my back up lately, and I'm really not up to wrenching much anymore)

***Scratches garage off list***

Some of these places today... You'd think they didn't need the business.

Nobody wants to deal with some oddball 30 year old Benz when they can earn $150/ hour by simply plugging in an obd2 scanner into a car and telling the owner they need a new compressor that they've done 10x before. So yeah, they really don't need your business.

Ain't that the truth. About the only thing new I will turn away are 7 series BMWs.

Then they shouldn't have taken his money in the first place. I'd much rather deal with a garage that says flat out that they won't work on my car than to half-ass a job and not stand behind it.

With 134a being phased out and R12 being priced like gold, the modern replacement being used in new cars is 1234yf - which is flammable and degrades into the same components as R152a. Soon enough you won't have a choice but to use something flammable.

Given the choice between broken A/C, Propane, R134a, and R152a, I'd choose the latter in a heartbeat.

LOL

How much does an R12 fill cost right now ? Just the refrigerant ?

Conversion to R152A?
 

I'm interested...my R134 converted AC is nice an cool until outside temps are in the high 90's+. Then kind of only a life safety kind of thing i.e. keeps the cabin down to mid to high 70's. I'd like 60's if I can get it.


When I converted from r12 (MB Indy Performed) I immediately noticed the reduced capability...all the vent mix gear is working fine.


What's involved?


Thanks in advance!

The best first move is a high capacity condenser FAN....
air across the condenser is THE bottle neck in ALL AC SYSTEMS.... mobile or stationary...

So...retrofit the stock forward mounted push fan with something that pushes more air? The existing OE forward mounted fan runs high speed when the AC is on.


Sounds easier than another AC conversion.

LMG - Long time no see :)
Do you have any idea what the largest CFM aux fan that will fit a w123 would be? I'm running a 16x24 PF condenser and a 16" Maradyne fan. It's quite a bit larger and supposedly more efficient by 36% vs the stock fan, but I can't imagine that I can get much more capacity. I do notice that Maradyne sells a higher current draw fan, I'll check mine tonight to make sure that's what I have.

http://www.peachparts.com/shopforum/...1&d=1496695388