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-   -   Can't locate fuse on heat pump circuit board (http://www.diychatroom.com/f17/cant-locate-fuse-heat-pump-circuit-board-158872/)

Ron2000 10-03-2012 06:23 PM

Can't locate fuse on heat pump circuit board
 
2 Attachment(s)
My home' s air stopped working. Checked heat- does not work not even fan. Fairly new home (less than 10 years old) Thermostat seems to be fine, can hear click sound when turning ON heat or air. Been trying to locate the fuse in heat pump's box to no luck. It has Honeywell circuit board. Could I get help in finding the fuse location? I snapped couple of pictures of the board.

Houston204 10-03-2012 06:46 PM

Probably doesn't have a fuse.
If it did, it would be in line with the fan relays.
Check the back of the circuit board for damage.

carmon 10-03-2012 06:47 PM

Quote:

Originally Posted by Ron2000 (Post 1023206)
My home' s air stopped working. Checked heat- does not work not even fan. Fairly new home (less than 10 years old) Thermostat seems to be fine, can hear click sound when turning ON heat or air. Been trying to locate the fuse in heat pump's box to no luck. It has Honeywell circuit board. Could I get help in finding the fuse location? I snapped couple of pictures of the board.

why are you looking for a fuse...do you have line voltage.....

epson 10-03-2012 07:24 PM

I’m no electrician but shouldn’t you check the main fuse box to see if a breaker is tripped? :whistling2:

Ron2000 10-03-2012 07:35 PM

Thanks for the quick response. Breakers are fine. Heat pump and outside air unit's capacitors are also checking good. Seems to be just blown fuse or is it possible they have this board without fuse. In that case any electric surge or short circuit could blow the board. Also outside unit is
getting power, I was able to run the fan with direct contacts.
How do I check if circuit board is good?

Ron2000 10-03-2012 07:36 PM

Quote:

Originally Posted by carmon (Post 1023224)
why are you looking for a fuse...do you have line voltage.....

Yes I have line voltage.

Ron2000 10-03-2012 07:41 PM

Quote:

Originally Posted by Houston204 (Post 1023222)
Probably doesn't have a fuse.
If it did, it would be in line with the fan relays.
Check the back of the circuit board for damage.

You think circuit board is bad? Do I pull out the board, and what
damage I am checking. Visual or with multimeter? I am mechanical
engineer but know little bit about electrical and HVAC

ben's plumbing 10-03-2012 07:56 PM

the clicking sound you hear....is it in thermostat,,,,if so confirm 24 volts on control board...and transformer...

beenthere 10-03-2012 08:12 PM

Yep, see if your transformer is putting out 24 volts.

Houston204 10-03-2012 08:14 PM

If it is the stat clicking check for 24VAC between R and C.

av-geek 10-04-2012 12:39 PM

can any of the low-voltage wire connections on his circuit board be jumpered and have the unit start for testing purposes? Whichever one it is, if the unit starts, the problem will then be between the control board, and the stat inside the house. If not, then it's this circuit board, pending it's got power

Houston204 10-04-2012 04:03 PM

R = 24 volt power
G = fan
W = heat strip
Y = compressor
C = 24 vac common

Jump R to G to run the fan.

Avoid jumping R to C since this would be a short and would damage the transformer.

Ron2000 10-04-2012 06:35 PM

Quote:

Originally Posted by Houston204 (Post 1023798)
R = 24 volt power
G = fan
W = heat strip
Y = compressor
C = 24 vac common

Jump R to G to run the fan.

Avoid jumping R to C since this would be a short and would damage the transformer.



Thanks all. I'll try tomorrow. Good thing it's in seventies here and I don't need heat/ air for few days and I can keep testing.

Big John Studd 10-05-2012 01:58 PM

Quote:

Originally Posted by Ron2000 (Post 1023288)
You think circuit board is bad? Do I pull out the board, and what
damage I am checking. Visual or with multimeter? I am mechanical
engineer but know little bit about electrical and HVAC

Cool! I am an electrical engineer! Similar thing happened to me a month or so a go with my ignition board. Visual inspection can tell you a lot. On mine a trace on the board had burned through. I repaired the trace, and it's back running fine. See link below for photo of what the burnt trace looked like (in this case).

http://www.diychatroom.com/f17/blowe...1/#post1004331

Ron2000 10-09-2012 04:49 PM

Quote:

Originally Posted by beenthere (Post 1023318)
Yep, see if your transformer is putting out 24 volts.

Yes that is it! I should have checked first thing, 0 output from the sec. Also little burning smell. Ordered new transformer on line. My only concern is if something else could be wrong on the circuit board. What if I install new transformer and it also fries. Thanks guys! great forum!


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