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OTRA heating problems
My 91 Marathon XL40 doesn’t seem to heat properly. I do not have a seperate dash air unit in the coach. First question is when I turn the rocker switch on the dash to heat does this trip a solenoid to allow hot coolant to cirtculate forward? If so where is this solenoid and how do I test it? Second question is do the circulating fans turn on also with this rocker switch? I do have one hot water valve in front of the radiator which I turn on in the fall and off in the spring. Am I doing things correctly??
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5 Replies
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The heater/H20 switch on the dash controls an auxillary pump to help circulate the coolant. The rotary temperature control is what you use to adjust the temperature, and the rotary fan switch controls the blower. This is for Prevost Drivers A/C. If you have bus A/C, I think it operates the same way on that vintage.
1999 XLV X-6872, liberty #440 -
That auxillary pump and valve for the driver heat- Is that the one in the evaporator bay?
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I think you have hit it on the head. Where is this auxillary pump for the engine collant? Again, should the circulating fans on lthe drivers side bay come on with this switch?
Thanks.
Whiskeybill
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The circulation pump is usually behind the front bumper mounted on the ceiling. I’m still not clear whether you have dash air and heat or OTR, so this info may be useless.
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Anytime someone uses the OTR term it should be specifically to mean the Prevost installed full coach heating and air conditioning.
The term has been used by folks that have a converter installed AC system to cool more of the coach than the dash or driver’s air can provide and while it is OK to use some terminology to describe such a system the use of OTR confuses those attempting to provide answers.
Prevost installed OTR has a circulating pump for coolant. It is in the evaporator bay of the OTR system.
Converters will sometimes go beyond what Prevost has installed, such as the Liberty use of a very large circulating pump installed as part of the Webasto system.
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