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.
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.