Author Topic: Windshield Defroster  (Read 1721 times)

Offline paul102a3

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Windshield Defroster
« on: May 29, 2009, 05:12:32 AM »
We took the bus on our very first overnight trip and had a great time. The only issue we had was a defective AC thermostat which has now been replaced.

When we left the campgrounds, there was a lot of dew and early morning mist. Turned on the windshield defrosters and got lots of cold air blowing but no hot air.

What are the first steps to resolve the problem? The bus is a 1988 102a3.

In looking at some older posts, I understand there is a gate valve in the engine bay that allows the coolant to circulate throughout the bus for heat. Is it possible this valve is stuck? If so, how can I tell?

There is also some kind of valve to the left of the drivers seat that I understood from the previous owner was for the drivers heat. Does this valve need to be on for the defrosters to work?

Any ideas or help would be appreciated












2001 Prevost XL II

Offline Ednj

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Re: Windshield Defroster
« Reply #1 on: May 29, 2009, 05:57:37 AM »




There is also some kind of valve to the left of the drivers seat that I understood from the previous owner was for the drivers heat. Does this valve need to be on for the defrosters to work?

Any ideas or help would be appreciated














Yes, it must be open.
I beleive turning to the left opens it.
MCI-9
Sussex county, Delaware.
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That's Not Oil Dripping under my Bus, It's Sweat from all that Horsepower.
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Offline buswarrior

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Re: Windshield Defroster
« Reply #2 on: May 31, 2009, 09:27:59 PM »
Hello Paul.

To the left of the driver, on the floor, do you have the handles and cables that pull and push up and down?

Two of them, one for the water valve, the other for fresh/recirculating air?

Some only have one handle for the water valve.

Is the picture still on it showing which direction to put it in for hot and cold?

No flow, no heat.

happy coaching!
buswarrior
Frozen North, Greater Toronto Area

Offline Jerry32

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Re: Windshield Defroster
« Reply #3 on: June 01, 2009, 05:19:36 AM »
The  valve for the driver just goes up and down . Jerry
1988 MCI 102A3 8V92TA 740

Offline buswarrior

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Re: Windshield Defroster
« Reply #4 on: June 01, 2009, 05:29:47 AM »
50:50 chance....

At the risk of being wrong, if the picture in my head is right way around,

Pull up to get full flow, push down to close it, somewhere in between to adjust the temp.

If you can locate the pipes under the driver from outside, the touch test will tell the tale, if the blower air doesn't.

Also, it was possible to airlock the heater core for the defroster on the older MC7-8-9, giving you no heat. I doubt that the 102 would be any different.
There is a bleeder fitting along the edge at the top of the core, you'll have to pull the access panels and have a look, should be where you can get at it.

happy coaching!
buswarrior

Frozen North, Greater Toronto Area