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 BillyHvac Your Own Question
BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22006
Experience:  Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
Type Your HVAC Question Here...
BillyHvac is online now
A new question is answered every 9 seconds

I have a trane xr90 and a honeywell minizone. No heat, but

Customer Question

I have a trane xr90 and a honeywell minizone. No heat, but the fan runs. Minizone shows no calls for heat, though all zones' thermostats are set high enough to call for heat. Furnace blinks steady red.
Submitted: 6 years ago.
Category: HVAC
Expert:  BillyHvac replied 6 years ago.



How many zones do you have ?



Customer: replied 6 years ago.
three zones
Expert:  BillyHvac replied 6 years ago.

Thank you...are you familiar with the inside of the mini zone control box?



Customer: replied 6 years ago.

yes, i have it open now.

Expert:  BillyHvac replied 6 years ago.

You will have a set of wires going to the furnace...rc, y, g, w you see the Rc and G?

and if so take a paper clip shaped in a U and touch one end to Rc and one end to G at the same time..5 seconds...tell me if fan starts in furnace.

Customer: replied 6 years ago.
nothing happens.
Expert:  BillyHvac replied 6 years ago.

there will be a transformer mounted somewhere with a 2 wire strand going to minzone.


Depending on model of minizone the 2 wires will go to Terminal 1 and Terminal you see those?



Customer: replied 6 years ago.
Yes. The transformer is on the right side of the panel. 2 wires: red and white.
Expert:  BillyHvac replied 6 years ago.

Do you have a meter to tell if the 2 wires have 24v present?



Customer: replied 6 years ago.
I own a meter, but it is not with me now (at home)--it's at my cabinetmaking shop about 10 minutes away. I can go and get it if required. Can we try something else without it first?
Expert:  BillyHvac replied 6 years ago.

Which model number minizone and I will see if we can proceed via another venue.



Customer: replied 6 years ago.
new info: furnace led is now blinking error code three. It was a steady single blink when I first asked fer help.

Can't find minizone model's not on the panel or cover.
Expert:  BillyHvac replied 6 years ago.

Well that changes things....


Is the exhaust fan running on the furnace?



Customer: replied 6 years ago.
No exhaust fan. The system fan (set on auto at thermostat) runs for about 5 min, so I rebooted mini zone. But this is interesting--the furnace LED is now blinking steady red.

No, wait. The red light just blinked fast (calling for heat), but nothing happened. Now the light is blinking three times again.
Expert:  BillyHvac replied 6 years ago. zone ok.....issue is with the exhaust fan motor in the top attached to vent pipe. Now the issue is exhaust motor getting power but not the motor not getting 120v. It is down to board or draft motor.



Customer: replied 6 years ago.
Holy Cow! The exhaust fan has 2 wires (white and green) going into it at the back end of the motor. Near the intake there's 2 black wires coming of the unit, and they go into a harness. On the other side of the harness, one black wire goes from one terminal to the other, apparently jumping those two wires.

Now here's the holy cow part. The white wire going to the motor has an inline fuse holder like in a car (or like cars used to have). There's no fuse in it!
Expert:  BillyHvac replied 6 years ago.


That is a new one for me......have you had this unit for long?



Customer: replied 6 years ago.
It's a new house-- a model for the development. I've lived here 5 years, and the furnace has always been a problem. Finally they had to get a Trane factory expert in. I'm not exactly sure what he did, but it was something to limit the input voltage. I know that sounds crazy to have to do in a new house, but that's what happened. That was two winters ago. That seemed to fix it--it stopped eating igniters.

It worked last winter. I had an air conditioning problem with condensation and some water on the floor over the summer. Had the unit worked on-- but not the furnace part (as far as I know). This is the first time we've needed heat this season.

So, should I put a fuse in there or cut out the fuse holder?
Expert:  BillyHvac replied 6 years ago.


In this particular case I would remove. The fuse is redundant anyway. I am wondering if the circuit board was damaged by condensation, or had a non stop inducer...something that would make someone remove the fuse for a reason.


I would bypass right now for further testing.. You can put back in the loop if need be later. Leave a couple inches of lead.



Customer: replied 6 years ago.
No, that wasn't just to recap, here's what's going on now. Starting with the red emergency switch on the side of the unit set to off and the thermostat of only only one zone on with temp set to 78.

Flip on emergency switch. The fan goes on (not the exhaust fan). Mini zone shows the one zone on, the led is orange. Steady flashing LED on furnace. After around 3-5 minutes, I can hear the vacuum switch operate, and the LED shows calling for heat. Nothing else happens. The call for heat lasts about 20 seconds, then the LED flashes 3 flashes. After another couple of minutes or so, the fan goes off. Minizone LED is now red. LED on furnace continues to flash 3 red.

Not sure how long if or when the call for heat LED would come on again.
Expert:  BillyHvac replied 6 years ago.


The missing piece is still the exhaust fan running.....when the led blinks steady fast, it is a call for heat which means exhaust fan should be running.....the 3 blink is air switch failure to close.......which is because the exhaust fan did not start.



Customer: replied 6 years ago.
Okay. It's the fan. That's good. Now, is there anything we can do to figure out what part needs to be replaced? Time to run out and get the meter?
Expert:  BillyHvac replied 6 years ago.


Get meter and verify 120v to motor...and then get model number and I can tell you where to get motor