Air Conditioner blows cold air when heater is on

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NICHOLEH

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Oct 5, 2018
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When we turn on the heater, the air conditioner blows out cold air. Does anyone know why? New owners.
 

Kevin Means

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Welcome to the RVForum. Is this occurring with the dash-air, or a roof, or basement AC unit? If you go into your profile, you can edit it and add some info about the year, make and type of RV you have. It helps others troubleshoot issues you may be having.

Kev
 

Lou Schneider

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Welcome to The RV Forum!

Some air conditioners have a heat strip or they are a heat pump that can blow either warm or cold air into the interior of the RV.

If you have a wall thermostat that controls both the furnace and a/c, it may be programmed to use the heat mode of the air conditioner to supplement the furnace, and either the heat strip has burned out or something is stopping the a/c from going into heat pump mode.

Again, more information on your setup would be helpful.
 

Frank B

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Apr 23, 2005
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Calgary, Alberta
Or, could it simply be that your control thermostat is set to the cooling position instead of heat? Our Coleman thermostat has a switch at the bottom with multiple slide positions. One side is heat, the other side is cool. Do you have the right one selected?
 

Arch Hoagland

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Welcome!!! 



How to make a signature for your RV so we can serve you better.

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Memtb

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North-Central Wyoming
?If?....you have a heatpump/ac, you may have a failed solenoid! There is a solenoid that ?switches? , the refrigerant flow....either giving you cooling or heating! If you are in the cooling mode, you will get ?hot? air discharge from the ac condenser on the roof. Just the opposite in the heat mode.
 

rbrdriver

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Visalia, CA
On our Sandpiper we used to have, you had fo set the fan speed to "auto" to keep it from doing that when furnace mode was turned on.
 

RVfixer

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Aug 12, 2012
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I'll bet that rdrdriver hit it on the nose!  On my Dometic thermostat you can cycle the fan through auto, Lo or HI.  If you leave the fan on low or high and then select furnace you will get both warm furnace air and cold fan air from the AC vent.  Select fan mode and then cycle through the modes to "Auto" or "AU" then select furnace.
 

StephenShort

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Feb 25, 2021
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Canada
I had that problem, too. The air conditioner was blowing cold air when the heating was on. And it was not a warm winter, so I had to solve the problem. I had to call a master from https://www.socool.sg/ to deal with it. I didn't really care what the problem was, as I wouldn't have figured it out anyway. I am too far away from technology. It took him a long time to explain it to me. And all I understood was that the air conditioner didn't seem to be set up correctly. I had everything done in a better way, and in addition, I had the air conditioner cleaned.
 

TonyL

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Dec 10, 2017
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UK
?If?....you have a heatpump/ac, you may have a failed solenoid! There is a solenoid that ?switches? , the refrigerant flow....either giving you cooling or heating! If you are in the cooling mode, you will get ?hot? air discharge from the ac condenser on the roof. Just the opposite in the heat mode.
It's called the reversing valve and it does what it says, it reverses the refrigerant flow. And yes, you are correct, it is operated by a solenoid.
 

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