Fuse will blow whenever the heat pump kicks in. Using an infinity thermostat, a four wire system. The furnace works fine and i am temporarily running a manual thermostat across R and W for now.
Which components in the heat pump would you suspect in blowing the 3 amp fuse in the furnace. Could it be the control board itself in the heat pump or the compressor contactor coil. Should i measure the resistance of all the components in the heat pump running low voltage?
Thanks in advance
carrier 58mcb-120 furnace and carrier 25hna660 heat pump
Ok, If 3 amp fuse is blowing in the air handler unit when switch is turned to cool check to see if outside unit jump starts and stops when this happens. If this is the case wiring is fine check main relay in outdoor unit. There will be a spring contact on main relay (Black relay close to where wires come into unit), check for corrosion or carbon build-up on little round contacts. If you can clean contacts with a small piece of sand paper. Make sure all breakers are off before removing cover! You might have to remove relay in order to clean it. Make sure you write down exact locations of any wires you remove. This should fix the problem.
The capasitor is in the outside unit , it is either round or oval in the electrical compartment , it has 2 or 3 termanels
Hi!!! Does your ac unit work fine?If not check your low voltage problem..You have a low voltage problem check the wire going out to your condensor make sure that they are not touching..Good luck..Check low voltage wires..short in progress..
Alright I had the same thing. 3 amp fuse keeps blowing. I don`t have an ac hooked to this like alot of these posts everywhere, just a furnace and a thermostat for heat. I`ve been working on this for 2 days and I can say after all this I found that I had an intermittent problem but didn`t know it. I`d check something and then 20 mins later I`d check it and it was differant. Make sure things you already checked are the same 20 mins later. Overall, i found thermostat wire wore thru were it enters the furnace and shorting to ground. i changed the board and thermostat, but as it turns out it was the short and no need for that stuff. The best way to fig this out is, disconect the thermostat at the board see if fuse blows, if so short inside furnace. If not, short out thermostat at board and while leaving thermostat wire DISCONNECTED. If blown then maybe board, or short, keep looking. If it doesnt short its the thermostat wire somewhere on its way to thermostat.
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Thank you for all your advise. The carrier system belongs to a client of mine and once the snow clears off the roads, i will go apply your advise on his system. I will report back on what i find on the low voltage short.
A question i had is, the swelling capacitor, is that a capacitor found on the control board?
Regards,
yes it could be either one or the capasitor, open the panel and look at the capasitor for swelling
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