Moisture In OTR Heater Bay

[Jcparmley]

Hello All

I purchased a 89 MCI c3 this past winter.  I noticed right away that there was moisture build up on the floor of the 1st bay right where the OTR Heater and blower compartment was.  It was damp and had a bunch of silicone pealing up (which was a good sign of water intrusion).  It also had a bunch of sand or salt like substance.  Anyhow, I removed the plywood door to the OTR Heater and Blower compartment expecting to see a leak or something but I couldn't find where the moisture was coming from.  I took some pics so you can see what I am talking about.  Where do you think this water is coming from?  Is this a common problem? 




This next pic you can see the old silicone on the floor at the base of the compartment and all the dirt and wet sand stuff.





My next step is to remove the plywood panel where the blowers go into to see if there is anything obvious that would cause this water intrusion.  I appreciate all your help. 

Jared

[neoneddy]

Is the moisture while you're driving or just in the rain?


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[richard5933]

Are you able to tell if the moisture is coming from the outside towards the inside of the bay, or is the phone call coming from inside the house?

If that bay is setup anything like the one in the GM, you've got both coolant lines and the evaporator coil in there. Both of these could be causing a problem (leaking coolant and/or condensate pooling up instead of draining out.) When we first got our 4108 the drain hole for the a/c was clogged up, and every time we ran the a/c condensate pooled up on the floor of the bay.

Or, it could be coming in from the outside, the roof, a leaking window, or any number of other places.

[Geoff]

Heater cores.

[brmax]

There is something? About coolant that never seems to dry.
Can you see or have there been signs of low engine coolant in the sight glass.


Good day

Floyd

[Jcparmley]

I will check the coolant in the sight glass.  I haven't been driving the bus because I have all the windows out preparing for a roof raise.  But when I purchased the bus before the tear down I noticed the dampness.  I also noticed the attempt to use silicone to seal out the moisture. 

There is something? About coolant that never seems to dry.
Can you see or have there been signs of low engine coolant in the sight glass.


Good day

Floyd

[brmax]

Hey Jared i'd be interested to see any pics on the construction phase, thats always cool.
On another note or back to the hvac center compartment.

I found there to be a double floor actually, it is a wee bit structural i guess. If your going to re use the compartment as original you want to be carefull. In that ( dont tear it out ) as its designed well for the purpose.

After finding and repairing the leak the floor could carefully be flooded with water and let drain dry. There is 3/4" insulation between these floor layers of aluminum and as ya know insulation takes a while to dry, especially when saturated with coolant.

May have to have some helper drain holes made/carefully through just the bottom floor sheet. There are drains but may have to be disassembled temporarily. This is just some stuff i found in my 9.

Good day and try to enjoy the build

Floyd