126 A/c
 

Okay - the continuing saga of 126 hvac systems. I had the system charged last year with R-12 and was assured it didn't leak. The guy told me the a/c worked very well, but he had left if running for hours to let the new charge take in the system. This year, I experience the same thing. The air is warm, and the center vents on the dash don't blow any air. As I drive, it finally starts coming out the center vents and just barely cools off. The problem is I don't use the car for long trips, so it NEVER gets cold in enough time. Any ideas?

Sounds like a low charge.

I can't imagine why this guy left it running for hours for the "charge to absorb."

Have a great day,

Thanks Larry. I think he left it running until it cooled off just to prove his point. It doesn't leak, but the charge never seems to last enough to cool off right away. I got a second opinion on whether it leaks and it came through fine. Even when I had it evacuated and charged once before, it was cool for a while and then died out. It's an 85 380SE that works fine otherwise. I know these babies were never meat locker cold to begin with, but I'm dying in our current heatwave.

The A/C involves three systems: the mechanical system w. freon, the vac control system and the electronic push button controls. Unless all 3 are working properly you can have cooling problems.

Are you sure that all the vac control elements are operating correctly? Especially check the fresh air flap located behind the glove box. It is easy to remove the glove box insert and visually inspect the flap operation with the A/C on and off. There are two vac elements that control the flap. When they fail the flap stays open and allows outside (hot) air into the cabin. The flap is open when it is toward the rear of the car and closed when toward the firewall.

Thanks Jack. I'll check it tomorrow. Good tip. That could be the culprit.

It sounds to me like a leak in the a/c system. You need to look at the sight glass after the system has run on max for about ten minutes. The sight glass should be clear, if not then you are low on refrigerant and most certainly have a leak.

Good luck,

Where is the sight glass located. The compressor is on the driver's side at the front of the engine correct?

Follow the lines. The sight glass is most often between the condensor and the evaporator. On the other MB's that I'm more familiar with it is on the passenger side behind the headlight assembly.

Good luck,

Hey Larry: What should it cost at a local indy to find an a/c leak?

How long is a rope?

It's impossible to say, it depends on too many different variables including the preferred leak detection method of the shop you take it to.

I would think that unless it is a really difficult leak to find, that an hour of labor should do it.

Good luck,

Larry,

Is it true that Benz's experience more a/c problems because they weren't designed for the hot climates of the U.S. It seems like they have more problems in proportion to American cars. I think GM has always had the best a/c systems, although sometimes in terrible cars.

Thanks for the responses - I know what I'm doing this weekend.

Jackmac

The Benz's of the late seventies through the eighties seemed to have the worst a/c systems. That said you have to divide the "a/c systems" into two categories, the refrigeration system itself and the Automatic Climate Control portion.

The refrigeration systems themselves use standard components much the same as most all cars and as a result their reliability is the same as most cars. The downfall of the refrigeration portion is their lack of cooling capacity. Remember Germany does not have the same climate as Florida or Texas.

The Automatic Climate Control is the source of most of the MB a/c problems. The cars that have manual a/c control in lieu of the ACC are pretty darn reliable albeit still plagued with marginal capacity systems.

My $0.02,