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Blower replacement, and condenser dirt!

1K views 4 replies 2 participants last post by  Stretch 
#1 · (Edited)
The cold weather has brought out a squeal from the blower bearings and I've been around long enough to know what it means. It means it is never going to get better and the only 'fix' is to replace the blower. I've done quite a few of these things, so getting at the blower was routine. Something like 20 minutes had it sitting on my toolbox. Sure enough there was play in the bearing on one end. A quick internet buy and I had a new bosch unit on the way. I've got lots of experience swapping wheels so I've got my fingers crossed that my luck will hold.

But here's where things got interesting. As I always do when I do a repair I clean the entire surrounding area so it looks new. One look inside the blower box told me this job was going to be bigger than first thought.

As you may know, 100% of the air flows through the AC evaporator core after it leaves the blower. It does this whether or not you have the AC on. My evaporator core was at least 2/3 blocked with grimey dirt caked on and into the core. Air was only getting through about 1/3 of the core! I did a UV light test and was pleased to find that there was no refrigerant oil residue so I didn't have to install a new core, but I did have to clean that one.

I sprayed the core down with a special cleaner, let it soak a minute, and blew it off with compressed air. Now it looked like new again, and I knew that when the blower was reinstalled my air flow would be up to spec.

[I took the opportunity, as long as it was out, to disassemble the wiper mechanism. As they usually are, it was full of hardened grease. I cleaned it up and lubed it with some synthetic bearing grease. I then oiled all the external joints with 3-in-1. Operates smooth as silk now.]

The first photo is probably familiar to everyone, the weak link in the Mercedes HVAC system. The second is the empty blower box with the evaporator just inside it. The last photo is the evaporator after cleaning. If you want to know what it looked like before throw a cupful of garden dirt onto your monitor.
 

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#2 ·
Oh you took it out that way

My car doesn't have air conditioning so those bits look alien to me - and as the engine was out I removed the dummy firewall bit behind the engine to get to my single fan blade blower motor.

Below my motor there's a water drain that drains to either side of the transmission - when I pulled it out of the car it was full of crud. You might want to have a check of yours, moisture and muck pooling near to electrickery isn't great
 
#3 ·
Oh you took it out that way

My car doesn't have air conditioning so those bits look alien to me - and as the engine was out I removed the dummy firewall bit behind the engine to get to my single fan blade blower motor.

Below my motor there's a water drain that drains to either side of the transmission - when I pulled it out of the car it was full of crud. You might want to have a check of yours, moisture and muck pooling near to electrickery isn't great
Yes, thanks for the tip. I had seen the drains when I was checking my trans mounts and had blown them out at that time. Od course, doing it that way (in reverse) meant all the crud which had been in the drains was now all over inside the blower box and adding to my evaporator clogging.:( It's all good now.
You only have a single wheel blower in the non-AC model? Hmmm, seems to me I would want to move a lot of air just for heating and defrosting purposes in Holland. To remove the blower on my car it was only neccessary to loosen the bulkhead and move it towards the engine. No hoses had to be removed which makes the job much easier and far less messy too.
As long as you brought up the subject, is it possible to buy replacement bulkhead pads, similar to hood/bonnet pads, so that area looks nice and sharp? I've never seen them.

To your comment about water and electricity. What a poor design the blower motor is for that kind of application. It is an open frame motor with conventional bearings sitting smack dab in the middle of a road salt fouled airstream. I'm sure someone at M-B thought more abut that setup for later models.

One last thing. A couple months ago I put a new blower in a customer's 380SL. He insisted on new OEM parts. It cost $1200. Not including labor.
 
#4 ·
Bulkhead pads are dealer only as far as I know. I haven't looked up the prices yet. I think I'm going to leave mine in a freshly painted state and see if it makes a big difference to the noise or not.
 
#5 ·
Oh yeah sometimes the dealer prices are much cheaper than aftermarket prices. Don't rule out the dealer thinking they're always more expensive. They might be the most expensive option for 90% of the time but that crucial 10% sometimes helps! (It might be less than 10% of course but whatever - save the cash where you can)
 
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