AC troubleshoting - where to start? - PeachParts Mercedes-Benz Forum

Catrinus · #1 06-07-2003, 08:32 PM

OK, you guys (especially Chuck!) have gotten me a long way in keeping my 73 280C going and fixing the little things that have gone bad. Now I guess it's time for a big thing. The AC doesn't work. Everything is hooked up, the indicator light on the console comes on, the engine feels a load, the compessor seems to be working, the fan is going, you can hear a flap closing (or is it opening?) in the system, but... it doesn't blow cold.

Is this a job beyond a DIYer? I seems logical that it's out of refrigerant, but I have NO IDEA how to check (or to check for leaks, for that matter). I do know that the car sat under a tree for over 5 years so it is very likely that it needs a re-charge, at least. Also, I'm not clear on what you can and cannot fill the system with these days.

Any help you can give me to pointing me in the right direction (even if your advice is "take it to a professional"!) would be greatly appreciated. Summer seemed to have gotten hear REAL early this year (traditionally it rains until July 5th in Portland!). I'm sweltering right now. PLEASE HELP BEFORE I MELT!!
Catrinus
Portland, OR
73 280C

#2 06-07-2003, 09:01 PM

it could be out of gas, goto an aircondition specialist and get a quote to see how it would cost to fill.

tosbt · #3 06-07-2003, 09:39 PM

Its probally needs a charge, mine sat up six years and I had it recharged and its blowing cold. Got lucky, hope you do the same.

cbdo · #4 06-07-2003, 11:07 PM

It's a pretty safe bet that it needs recharging, and the refrigerant will probably be the old stuff; wouldn't expect a 134 conversion to have been done on this car.

Catrinus · #5 06-08-2003, 11:32 AM

Thanks for the advice, guys. Two follow up questions:
1. Can most A/C shops work on these, or do I need to go to a Mercede$ $pecialist?
2. Does the shop check for leaks BEFORE putting in the gas? I don't want them to fill it up only to tell me it leaks (I hate wasting money, I guess!).

I agree, though, it does sound and feel like everything should be working so I'm hoping it just needs a recharge. What would be a fair price to expect for a recharge?

Thanks again,
Catrinus

#6 06-08-2003, 12:04 PM

Well, I have to get mine regassed soon, before summer. I'm going to ask them to replace all hoses reguardless of there current condition. I can't imagine hoses being a very expensive item.

engatwork · #7 06-08-2003, 12:29 PM

Quote:

I can't imagine hoses being a very expensive item.

You are going to be shocked to say the least

. Your best bet will be to try to find a place where you can get the hoses rebuilt.

ctaylor738 · #8 06-08-2003, 12:40 PM

Any competent AC shop can handle this. Some places have a reasonably priced system check where they will add a pound of freon along with a dye that shows up under UV light and get the system operating, then check for leaks. They should also use a sniffer to test the air coming out of the vents for leakage.

I would have that test done, then have them drain the system, attend to any leaks, and install a new drier.

If the system has not worked for a long time, you should get a new drier bottle bottle. They should then evacuate the system completely and recharge it.

Most good shops have access to a specialty shop that can rebuild the hoses at a fraction of the cost of new ones if that is needed.

Don't get talked into an R134 conversion - put the money into getting a nice tight R12 system, IMHO.

#9 06-08-2003, 07:40 PM

Quote:

Originally posted by engatwork
You are going to be shocked to say the least. Your best bet will be to try to find a place where you can get the hoses rebuilt.

Why wouldn't an air conditioner place beable to do the same?
I don't see anything special about the current hoses.

engatwork · #10 06-08-2003, 07:52 PM

Sorry about that, let me clarify. New hoses are out of this world for pricing. The way I get hoses rebuilt is to remove them, take them to a place called Tubes N Hoses and have them rebuilt. ALOT cheaper than new. I'm not sure a/c repair shops rebuild them in this area.

cbdo · #11 06-08-2003, 10:36 PM

One possible refinement to Chuck's suggestion: Get the new drier bottle, have the techs check the system once-over, and if it's ready for them to charge have them do so with the flourescent tracer. If they can identify leaks in the shop, get them fixed and proceed. If they DON'T see leaks in the shop, run with the system for a month or so and then have them check for tracer.
I'm basing that on my shop's doing exactly that on my car; their info to me was that a slow leak won't show in the shop and is much more apparent after the system's been used a while.

240 Ed · #12 06-13-2003, 07:19 AM

You are in LUCK!

Your system has lost a little freon (R12), enough so it doesn't cool properly. After sitting for 5 years (!), it shouldn't have any freon in it, but yours definetely does because the compressor still works.
The reason I say this is because there is a switch which senses the refridgerant pressure. This switch controls the electric clutch at the front of the compressor. If there is no pressure, the pump will not run. (this saves the compressor from running when there is no charge. The lubricating oil for the compressor is suspended in the freon)

So, you have enough charge there to run the compressor. Which means that the system is still tight. You only need to add some make up, then the system will blow cold!

After sitting for that long, there is the inevidetable loss around the compressor seal. This is why it is advisable to run your compressor year round, to keep this seal lubed and sealed.

Any AC place will add some R12 for you. Probably $100, I am guessing.

The R12 is the best, so try to keep it. I just hope that the shop doesn't pull some scam and leak all the R12 out, and try to sell you a new compressor for the 134 stuff.
Perhaps if you act knowledgable and you find a good place, you can keep your R12 system intact.

#13 06-13-2003, 10:05 AM

the york compressors can not handle the conversion, will wreck the system.in my neck of the woods to redo mine, hoses, compressor dryer flush fill was 600.00. A bit much?

los angeles ca.

Catrinus · #14 06-13-2003, 06:24 PM

Thanks, Ed -- this was exactly the advice I was seeking. I am going to take it to a local radiator/AC shop here in town which has an excellent reputation and ask them to charge it with R12. Sounds like that's all it will need (I'll keep my fingers crossed and let you all know how it turns out).

Catrinus
73 280C

ctaylor738 · #15 06-14-2003, 09:09 AM

Worth a try, but a new drier bottle is almost inevitable.