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Tim H.
Tim H., HVAC Professional
Category: HVAC
Satisfied Customers: 3971
Experience:  Experienced in all aspects of HVAC, both residential and commercial.
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I have 2 sterling unit heaters that I am having problems

Customer Question

I have 2 sterling unit heaters that I am having problems with. One is a TF300 and the other a TF400. The TF 300 will fire 3 times and run for about 5 seconds and then go into lockout mode. The 400 will fire and come on but the fans will not kick in and the limit shuts the burners down.
Submitted: 1 year ago.
Category: HVAC
Expert:  Tim H. replied 1 year ago.

Hi, I'm Tim and I'm an HVAC expert here to assist you with your questions. Please provide all information I request as it makes it more difficult to troubleshoot something when I'm not there onsite. Essentially, you become my eyes and ears. Thanks for the opportunity to help. At the end of our dialog, you will have a chance to rate my service, but please wait until we are finished and you're satisfied you have all the information you need.

Sounds like two separate problems. On the TF300, try cleaning the flame sensor. On the other one, could either be a bad fan switch or fan motor. I would need voltage readings at the unit to confirm which it is.

Customer: replied 1 year ago.
I will try to clean the flame sensor on the tf300, there is not a fan swith on the 400 but a pressure switch that is connected to the motor on the exhaust, I have tried cleaning the vinyl tude, cutting and reattaching to no avail. One fan motor is brand new, just installed today and the other works fine when wired direct.
Expert:  Tim H. replied 1 year ago.

If the motor is not getting voltage, then it would be a bad board.

Customer: replied 1 year ago.
I will go now and try to clean the flame sensor. I will also check the voltage on the 400 and get back with you shortly.
Expert:  Tim H. replied 1 year ago.

OK, thanks.

Customer: replied 1 year ago.
cleaned the flame detector to no avail, replaced the flame detector the next day thinking it was still at fault and cleaned the terminal ends as well and still no change. Called in a service tech yesterday and he said the problem was in the circuit board. The problem with the other heater was a fan anticipator.I know it is hard to diagnose problems without being there but these were a little more difficult than normal.
Expert:  Tim H. replied 1 year ago.

Thanks for the update. Yes, it is difficult to diagnose over the internet, but we have successfully helped many people despite that setback. Yes, good luck! Thank you for using Just Answer and please don't forget to rate my service as that's how experts get paid (Thanks in advance for any bonus left). Otherwise experts work at their own time and expense. Feel free to post back with any additional questions.

Customer: replied 1 year ago.
the expert was very knowledgeable but unfortunely this time he was not able to solve my problem and I did have to call in a service tech to get the problem resolved. I would hope my credit card would not be charged in this case. thanks, Mark
Expert:  Tim H. replied 1 year ago.

Thanks again