Heat Pump Not Heating

[restlesswind]

Our fifth wheel has a heat pump on the roof for heating /cooling.
The cooling part is working fine.
The heating part is not co-operating at all. It tries to start,then shuts down.It is supposed to then switch over to the gas furnace,but it does not.
The outside temp was close to 65f. The air conditioner cools just fine. Any ideas as to what to look for.

I'm thinking maybe the thermostat But(?)
We do not need the heat pump heater all that much because we do have the gas side but I do want it to work.
Thanks
Ed

[Duck]

Sometimes those fancy T stats are just too smart.
Don

[restlesswind]

Update for my Heatpump "problem"
I called the Mfg service department for advice.(Great people,BTW)
When we stated to walk thru the "problem" I switched the T-stat to
"electric" The HP came on and blew warm air! Just the way it should!
I don't have any idea why it did not work before,but it's working fine now.
I'll check it again in the next couple of days to make sure it's going to keep working.
I'm thinking that the 'lectric grimlin left to go confuse someone else.

[restlesswind]

Just to answer a couple of things about my "problem"
I DO have a heat pump! It is on the roof.I also have the gas furnace in the basement.
When the outside temp is well above 40,and I have the wall Tstat set to "Electric Heat" The rooftop unit should come on and heat the trailer thru the ceiling air outlets.It used to work fine.It no longer does.It does what it should to do,if the HP can not supply heat,it will automaticly switch over to "Gas mode" and supply heat, thru the floor vents, from the gas furnace in the basement.

That's the "problem"...no heat from the rooftop HP.

I can switch over to "Cool" and the HP works just fine.
I can switch to "Gas mode "and the basement furnace heats the trailer with no problem.
There Are NO heat strips in the HP unit.
It seems as though the HP is not reversing to heat mode.

I realize that I can do without the HP heat and just use gas,but sometimes free electric over using my propane is the better deal.
I have a tech comming tomorrow,I'll post whatever he finds.
Thanks again for all the suggestions and advice
Ed

[dougrainer]

SuperDutyFiver wrote:
Wait a second-if the stat says 'furnace' or 'electric' it's a stat for a AC with heat strip isn't it?

When the stat has multiple modes-furnace/fan/AC/electric-the electric option is usually for the heat strip in the A/C. Are you sure that it's a heat pump-I know it's a dumb question? If it's got a heat strip it could be unplugged in the rooftop unit. Usually the heat pump stat specifically says 'heat pump' as an option.

I agree that if it is a heat pump and the 'ambient room thermistor'(room air temp sensor) is going bad it may not run on heat but could cool and or run the furnace.

How is the unit working when it is on A/C? When on furnace does everything work correctly? The time delays on the board could be screwed up-giving it time and being patient can be critical with heat pumps switching modes too.

Another question-is the 9000 a basement unit? and is the furnace integral to it? Could you have a bad breaker? It's probably time to break out the old tester and a screwdriver! 😉

Does anyone know if the room temp sensor is in the thermostat or rooftop unit? Or are there a few of them scattered around the unit?

NO. RVP uses the Gas and Electric designation for HP and Furnace. 90000 is a roof top unit. Since he has a 5th wheel, I doubt he has no other room sensor other than the wall tstat. AND, as I asked, the wall tstat does state HP which means it is a HP tstat. Doug

[SuperDutyFiver]

Wait a second-if the stat says 'furnace' or 'electric' it's a stat for a AC with heat strip isn't it?

When the stat has multiple modes-furnace/fan/AC/electric-the electric option is usually for the heat strip in the A/C. Are you sure that it's a heat pump-I know it's a dumb question? If it's got a heat strip it could be unplugged in the rooftop unit. Usually the heat pump stat specifically says 'heat pump' as an option.

I agree that if it is a heat pump and the 'ambient room thermistor'(room air temp sensor) is going bad it may not run on heat but could cool and or run the furnace.

How is the unit working when it is on A/C? When on furnace does everything work correctly? The time delays on the board could be screwed up-giving it time and being patient can be critical with heat pumps switching modes too.

Another question-is the 9000 a basement unit? and is the furnace integral to it? Could you have a bad breaker? It's probably time to break out the old tester and a screwdriver! 😉

Does anyone know if the room temp sensor is in the thermostat or rooftop unit? Or are there a few of them scattered around the unit?

[chevylover1965]

Same thing happened to me a few months ago. It turned out to be a bad thermostat wall unit. Mine was a Coleman for my 2006 Phaeton. Good luck

Jerry

[dougrainer]

restlesswind wrote:

dougrainer wrote:
If the outdoor Ambient condenser coil thermistor is defective or not connected all HP functions will shut down. This is ONLY RVP HP's and will not affect the COOL mode. So, if no fan or compressor, then I would check the condition of the condenser thermister. I have never seen one fail, so, I would suspect it is not connected to the upper control board. Doug

So could that condition("no connection to the upper control board")
be caused by a loose connection at the T stat ?

So far I have not gotten any tools out.Trying to get some education here before I really mess things up.
Thanks for the help from everyboby
Ed

Probably NOT the tstat. The wiring all goes to a control board in the top unit in front of the Evaporator. HAS the HP functioned before and this problem just came up? Doug

[restlesswind]

dougrainer wrote:
If the outdoor Ambient condenser coil thermistor is defective or not connected all HP functions will shut down. This is ONLY RVP HP's and will not affect the COOL mode. So, if no fan or compressor, then I would check the condition of the condenser thermister. I have never seen one fail, so, I would suspect it is not connected to the upper control board. Doug

So could that condition("no connection to the upper control board")
be caused by a loose connection at the T stat ?

So far I have not gotten any tools out.Trying to get some education here before I really mess things up.
Thanks for the help from everyboby
Ed

[dougrainer]

If the outdoor Ambient condenser coil thermistor is defective or not connected all HP functions will shut down. This is ONLY RVP HP's and will not affect the COOL mode. So, if no fan or compressor, then I would check the condition of the condenser thermister. I have never seen one fail, so, I would suspect it is not connected to the upper control board. Doug

[dougrainer]

Duck wrote:

TennesseeBob wrote:
Might be your reversing valve stuck or not working

X2
Don

As I stated, THAT will not cause the system to not come on. It will still come on but either Heat all the time or Cool all the time. I do not know the default on RVP, but older (5 button and 4 button) Dometic's the default if the valve failed was Heat all the time. The new Single Zone and 12 button Dometic's the default is Cool all the time if the valve fails. Doug

[Duck]

TennesseeBob wrote:
Might be your reversing valve stuck or not working

X2
Don

[aruba5er]

Won't venture a guess on what could be wrong but, I have a heat pump at home and it works very effectivly to around 30 degrees. after that it becomes cheaper to heat with gas. Now i'm talking natural gas. Because propane costs more, it may be cheaper to continue using HP down to 25. There is always heat in the air, all the way down to absolute like -245 but it is not practical. the electric used would not be offset by the heat.

[restlesswind]

dougrainer wrote:
1. Your Furnace should operate regardless of the HP. The tstat will have the option of either gas furnace or the HP function. You do NOT have to rely on the HP kicking out and then wait for the furnace to come on. repost after you have tried the Gas furnace only mode.
2. RVP, all the HP does is reverse the flow of coolant to Heat rather than cool. You have a reversing valve that is electrically operated to open and close the reversing valve to either Heat or Cool. THAT valve, if failed would NOT keep the unit from coming ON.
3. Please state exactly what happens when you go to HP. Does it NOT come on at all? Does the fan come ON but when the compressor tries to start it kicks out?
4. IF your wall tstat does NOT state HP on the cover name or does NOT have a "Gas Heat" and a "Electric Heat"(this is the HP side) switch, you do NOT have the correct Tstat for you system. It will usually state similar to ---RV Comfort.HP that designates a HP wall tstat.
Since you state a 90000 series your wall tstat should have a LCD display. Does it? Doug

The Tstat does have gas or elect position
When it is on "gas" I get heat
On "electric",no heat,no blower.
If the stat is turned high enough,on electric,it will kick over to gas mode and heat the trailer.
The Tstat is the original one that came in the trailer ( We bought the trailer new)
It is the RV Comfort HP,Coleman Mach Model With an LCD display.
We use the gas mode more often that elect,as was said,it is more quite.But getting ready to travel in the spring I like to use the CG power and save the propane.
Even if I can't get it working,with your help,at least I won't seem like a complete dummy when/if I call a tech to fix it.

[TennesseeBob]

Might be your reversing valve stuck or not working