Blower works!...No air in cabin. - PeachParts Mercedes-Benz Forum

nestorb98 · #1 06-20-2013, 04:09 PM

My 1991 300TE has found a new way to stump me. The ac/heater fan works on both speeds, I've taken it apart two times and both times the squirrel cages spin wonderfully, but inside the cabin...bubkus!

Checkes fuses, connections, nothing.

Help!

Thanks in advance.

Mike D · #2 06-20-2013, 04:55 PM

So does the fan spin in the car and you don't get air flow or does the fan not actuate?

Does the defroster work (air flow-wise)?

The vents are operated by a series of vacuum diaphragms and if they don't switch the air flow you won't get circulation.

nestorb98 · #3 06-20-2013, 05:27 PM

fan spins just fine and in both hi, low and stops in off setting.

Defroster...nothing.

So...what vacuum diaphragms and where do I test them?

Thanks you.

nestorb98 · #4 06-20-2013, 05:29 PM

So you know I replaced the fan motor in my 1995 E230 wagon and that one never gave me this problem.

Mike D · #5 06-20-2013, 05:59 PM

Does the A/C compressor engage? Just trying to get all the facts straight.

What was the last thing you repaired on the car, no matter how remote it seems from the A/C.

I'm not hip to the W124's so I can't really help you with the vacuum diagrams but there are plenty of people on this board who do know.

Shucks, you don't need A/C yet anyway. It ain't got hot, yet!

"Can't be but 114 in the shade".

ps2cho · #6 06-20-2013, 06:45 PM

pods or pod control unit toast.
Pull glovebox insides and test all the vacuum lines coming from the control unit. Can't miss it.

I feel for you...I only got my A/C working last week and have been surviving the Arizona heat for the last few months.

A/C R134a pressures too high. I'm lost. Ideas?
Post #43 for pod testing
Post #61 for pod replacement

nestorb98 · #7 06-20-2013, 10:11 PM

thank you for your answers...

A/C compressor is definitely engaging.

If you get really close to the A/C vents you can feel really cold air.

Last thing repaired was a window regulator.

Just read the article on the actuators...so Ps2cho, you read my mind...I'm on my way there!

I think at 240,000 taking apart the dash might just be the thing. Why is it easier to take out the fan motor than to remove the glove box?

Now to the finals!

jay_bob · #8 06-20-2013, 10:50 PM

I am surpried you are getting no air flow at all anywhere. Normally the vacuum pods that open the air flow doors are rigged so that if there is a total loss of vacuum the door positions default to defrost mode and the air goes out the base of the windshield.

Before you pull the entire dash, try pulling out the glove box liner first. The vacuum switcher manifold is accessible from that location. It has one input hose (on the end) and 7 output hoses to the pods. It has 7 electrically operated valves controlled by the pushbutton unit.

Obtain a mity-vac (hazard frought tools has one on special this week) and check the green incoming hose from the engine to see if it has vacuum. Then try applying vacuum to the various output hoses and see if you can move the doors to gain some airflow.

The dashboard is not terribly difficult in a 124 to remove if it turns out your problem is the pods.

I would also go to either the M-B site or w124-zone.com and get a copy of the FSM. There is an excellent troubleshooting procedure in there for the ACC.

JamesDean · #9 06-21-2013, 10:56 AM

On my 201 I had the same problem! I lost air flow. Tore everything apart, found the squirrel cage motor was running no problem. Just no air flow! Turned out that my evaporator had been completely blocked up...

Not sure if the same can happen to the 124 as its designed differently.