How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask HVAC Guru Your Own Question
HVAC Guru
HVAC Guru, HVAC TECH
Category: HVAC
Satisfied Customers: 14210
Experience:  15yrs in the HVAC industry with certificates and degrees.
21107370
Type Your HVAC Question Here...
HVAC Guru is online now
A new question is answered every 9 seconds

Amana pth operates in hoth cool and heat pump mode from

Customer Question

amana pth operates in hoth cool and heat pump mode from front panel and diagnostic run produces heat and cool ( not sure if in correct order - im not on site)
But with remote wired tstat it has to be shuttled between B and O valve sense to get the unit to function in heat/cool mode. Otherwise tstat only cools (or heats depending on active heat or active cool) regardless of whether tstat is calling for heat or cool. I have another identical unit having identical tstat connection that works as expected. Could the solenoid on the reversing valve have reversed polarity form the factory?
I have swapped out the control board and the tstat to no avail.
Submitted: 3 months ago.
Category: HVAC
Expert:  HVAC Guru replied 3 months ago.

Hello, one minute while I get some information together.

Expert:  HVAC Guru replied 3 months ago.

Hello and thanks for using this service! If you are a JA Member I would like to personally thank you and welcome you back! I am HVAC Guru an extremely experienced tech on the site and I try to get to as many customers as I can. NOTE it takes time for me to type research and add links so please wait for me to respond back I can only do this so fast. Secondly, I do not know your skill level so please try and let me know if I am going beyond your knowledge or comfort zone thanks! I strive for a 5 star rating from everyone especially our JA members.

Did you go into the installer menu on the thermostat and set it up for a heat pump with the correct setting for the crossover valve?

Customer: replied 3 months ago.
as I indicated I have an identical unit wired and configured the same that works as expected.
Expert:  HVAC Guru replied 3 months ago.

Then something would be wrong with the changeover valve have you tried switch the wires on the valve or at the thermostat?

Customer: replied 3 months ago.
no . I have tried all combinations of 'B' and 'O' on the tstat and the unit control board configuration . I get either heat operation regardless of tstat mode or cool mode regardless of tstat set to cool or heat.
Customer: replied 3 months ago.
Unit is heating now. But if the tstat is set to cool the unit continues to heat.
I can get the unit cool by changing either the tstat or unit to the opposite active reversal sense.
Expert:  HVAC Guru replied 3 months ago.

Do you have a separate O and B wire?

Customer: replied 3 months ago.
but if I do this it only cools regardless of whether tstat calls for heat or cooling
Expert:  HVAC Guru replied 3 months ago.

Do you have a two wires O and B or just one?

Customer: replied 3 months ago.
No. The configuration on thermostat is soft, as is the configuration on PTAC inself
Expert:  HVAC Guru replied 3 months ago.

Yes but on the thermostat do you just have an o/B terminal with one wire or two separate wires?

Customer: replied 3 months ago.
one wire
Expert:  HVAC Guru replied 3 months ago.

OK in the thermostat setting change the crossover valve to the other setting and try it.

Expert:  HVAC Guru replied 3 months ago.

Also do you have an O and B terminal on the thermostat or just an O/B terminal?

Customer: replied 3 months ago.
O/B on both ends
Expert:  HVAC Guru replied 3 months ago.

Can you reverse the wires to the valve?

Customer: replied 3 months ago.
I'm not on site. That is my question: is reversing polarity on the valve terminals inside the PTAC unit worth trying? I will be able to go onsite tomorrow and fiddle some more. I have to give the tenants notice.
Expert:  HVAC Guru replied 3 months ago.

Yes I would say reverse polarity is all you have left at this point, worth trying and it can correct that.

All I ask is please use the Star Rating Link at the top of your page before leaving, that is the only way I am credited through the site, tips are appreciated....HAPPY THANKSGIVING!

Customer: replied 3 months ago.
I will try this tomorrow. From the schematic the rv solenoid is 230v. Is it possible that the line connections are the problem?
Expert:  HVAC Guru replied 3 months ago.

Yes very possible!

Customer: replied 3 months ago.
I'll check for a broken wire between the thermostat and reversing valve. That's the only thing making sense to me.
Reversing polarity on the solenoid would only matter if the core was magnetic.
Expert:  HVAC Guru replied 3 months ago.

Try it and see what happens