Heat Pump Not Heating

Sometimes those fancy T stats are just too smart.
Don

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.

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

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

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?

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

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

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

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

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