Defroster Q's

HoosierDaddy · 10-05-2009, 01:02 AM

Trying to get my front heat defrost working.I have 12V at the dash board control panel but the blower motors wont run. I found two Blue/White stripe wires in the center stack. I think they went to the switch labeled "aux defrost??"( Not sure ,,that area of the stack was bashed up by the vandals) If I jump 12V to one of those wires one of the blower motors runs. I get air out of 4 of the vents at the center windshield. Is there a "heater core" to bring engine heat to the defrost? A wiring schematic would help but I have not been able to find one.

folivier · 10-05-2009, 01:22 AM

The way I understand it, there is a pump on driver's side of engine with a solenoid to turn it on. This pumps coolant to the front and is controlled with the heat switch on hvac controls. I would think there is a heater core but not sure where. I hope to try out the defroster/heater and also the engine pre-heat if we ever get any cold weather this winter.

encantotom · 10-05-2009, 01:32 AM

ah yes.....

the aux defrost is to engage extra blowers in the plenum. the plenum and heater core are located behind the panel to the right of the genny blower in the front passenger compartment. remove the two screws for the black aluminum angled cover at the front, take that piece out, then the board with insulation that forms the right hand wall of the genny blower compartment slides out towards you.

then you will see the plenum that has those blowers and heater core in it.

i have done extensive work in there so call me if you need to talk through it.

as for the pump for the coolant for the front heater core, each coach was done slightly differently. mine is different than michaels, different than davids, different than wallys etc. but i know enough to be dangerous about them now.

once you take that metal side panel off the plenum, you will see the blowers and you can see what wires go to what blower.

also, only some of the vents below the windshield are actually hooked up. about half of them are dummys. that is why you only got air out of 4 of them.

the defrost system on these year coaches is dismal.

tom

Summersgal · 10-25-2009, 05:14 AM

Tom,

Before I install my blower in the blower bay, I thought I would see if I could get the auxiliary defrost working. There are three blowers located here, the one on the far left in the attached picture is operated by a 3 position switch on the dash labeled floor, it works and has three speeds. I can only get the other two to come on when the air and heating fan control switch is in the high position, both blowers come on (i do not know if the speed is low, medium or high). Any other position of the switch and the blowers shut off. With both running I can feel a little air coming out of the two round vents on the dash and one vent located in the passengers right knee area. Rotation is correct on both blowers. I am beginning to wonder if this is worth pursuing or maybe take out the unit and turn the space into storage. There is also a two position switch below the battery merge switch that I have no Idea what it controls, I have not tried to trace out the wires yet. any suggestions would be appreciated.

Jeff

fulltiming · 10-25-2009, 02:13 PM

Jeff, you could have a problem with the switch unit itself (Tom has replaced his). There is a small board next to each blower that changes the speeds on the fans but if two separate fans are only coming one at one setting, I would suspect the switch on the dash. I don't have the floor control you do but then my heat and air come out of the same vents. It only changes if I move the switches to defrost. I would guess that the Floor control would shift the air flow to the floor vents instead of the dash vents.

encantotom · 10-25-2009, 08:06 PM

hi,

my guess is the switch for the fan speeds on the heater A/C control panel, the one on the far right is bad.

you should be able to tell with a meter.

i did replace the pushbutton switch control module on the back of the panel with a NOS one i got on ebay for 5 bucks.

the actual complete panel is a late 80's dodge ramcharger and i just recently bought a like new one to replace the one i have. i paid 35 bucks plus shipping for it. if the switch is bad, you might just have to find a complete panel.

fyi, there are 3 active vacuum lines on the back of the panel as well. a black, blue and red. the black is the incoming vacuum, the other two are the ones that follow the lines down to the plenum you have open and control the outside vent air louver on the bottom of the plenum as you look up from the ground and the other is for defrost.

the panel has an extra microswitch that is attached to the slide heat/coollever that newell installed to turn on and off the coolant pumps and valves for the various coolant heaters in the coach.

if you need to talk through it, i am PM'ng you my cell phone number...

tom

Summersgal · 10-26-2009, 01:02 AM

Thank you for the replies, I made a little head way this afternoon. I unplugged the connector on the back of the switch and cleaned everything up. I then unplugged the connectors on the resistor boards on each motor and plugged them back up. All 3 speeds are now working, the 3 different voltages are 10.5 volts, 11.4 volts and 12.5 volts. Everything seemed to be going great until the fan on the far right starting growling and speeding up and down. Pulled the motor out and took it apart, there was nothing left of the brushes. The commutator is in pretty bad shape too. I will try and find some replacement motors tomorrow. If I can't find any, I may just clean the comms up and replace the brushes. I really appreciate the heads up on the vacuum lines, I won't state how many minutes were lost before I realized (NO AIR = NO VACUUM). It seems there are two coils in this unit, one for heat and one for AC(??). The switch labeled floor activates a separate system of two fans blowing across an AC coil located in front of the two front air tanks underneath the coach. The one labeled Upper, turns on the blower for the AC unit located in the overhead on the passenger side. I don't believe there's any freon left in the system.

Quote:

the panel has an extra microswitch that is attached to the slide heat/coollever that newell installed to turn on and off the coolant pumps and valves for the various coolant heaters in the coach.

I have noticed there are some pumps and lots of wires and relays mounted in front of this bay, I do not know if these are functioning or not.

I really do appreciate the reply's to all my post's, I hope you guys don't get tired of all my questions. Thank you very much for the phone number Tom.

Jeff