Gas and Oil Home Heating Furnaces - Blower Fan Problem

I have been trying to find out what is wrong with the blower fan on my coleman/evcon electric AC/Heat for more than a month now! The blower will not power up at the thermostat "ON" position. The heat came on for a few minutes, then cut off and it also will not power up. The AC compressor comes on with manual contact at the contactor on the compressor. I get 240 VAC to the transformer and to the Run Capacitor and to the Fan Relay on the inside unit where the heater, AC Coil and Blower are. I have no 24-voltage coming out of the secondary of the transformer. I replaced the transformer and the Fan Relay. I have a problem in the control circuit somewhere. I checked out the thermistat and it appears to be ok as far as continuity and the coil operates when called upon for heat or cool. I have already gone through two transformers! What could be shorting out my transformer in the Control Circuit? I checked the Motor in an ambient condition by checking resistance with a VOM across the windings which are connected to a Start/Run Capacitor and I get 74 Ohms. The fan blades and rotor turn with ease and their appears to be no sign of overheating! I am out of ideas! What on earth could have blown my transformer? Surely not the Capacitor?!:confused: :confused:

Something on the 24 volt side is shorting or drawing high current

First off, try and keep high voltage problems and low voltage problems seperated. A high voltage fan motor won't work unless a low voltage (completed) circuit tells it to. I'd make sure you have at least a 40 VA secondary on the xformer. Keep in mind the stat is only a swiitch to turn a widget(s) on or off. Kill all power to both id and od units. Disconnect the stat wires, marking them for re-connecting and ohm your lowvoltage wires for a ground, including those in the heat section. You want to check for short circuits with your ohmeter which would blow the secondary quickly. If nothing found then reconnect. Assuming all of the relays are good then one could be operating at a high resistence. If your unit had a low voltage solonoid, which is unlikely, then it could be causing an overload, neccesitating a heavier xformer. Check all your low voltage wires for chaffing and loose terminals.

Thankyou Rick for responding. That is what everyone says. The problem is on the 24-volt Control side.

Thankyou ahasbeen for also responding. Please be more descriptive please for this neverhasbeen about what exactly are the stat wires. I get the rest of it. Thankyou for your help. You have given me something new to work with. pindy:cool:

The general accepted color coding for stat wires is red (R) for power from the xformer, green (G) for fan, yellow (Y) for compressor, white (W) for 1st stage heat, blue(Bl) for 2nd stage heat or black (B). You can't always depend on these colors tho. In general, what needs to be done in your case is, with all power off, ohm out each circuit from R, thru the stat to one side of the circuits' coil.Do this in both heat and cool mode. If no shorts or ground are found then you might want to go from the other side of the coil back to the other side of the xformer to check for short or ground. You will have only little resistance for the above checks. If you find high resistance, then either you've found a problem or you're reading thru a relay coil or some resistive device. All switching and signaling goes from R to one side of a relay coil. The other side of the coil goes straight to the opposite side of the xformer. At least thats the way it should be unless joe blow did the wiring. My guess is your problem might be in the heater unit low voltage - a klixon overload, heater fuselink or maybe a heat sequencer, or at the compressor contactor. Both the od and id units should have wiring digrams. If you don't find the problem, quit spinning your wheels and get a service tech before your units smokes

Thankyou Ty(ahasbeen)! You have given me a lot of info! I truelly indeed appreciate your effort to help and inform me! I have gained a huge education in this project I have so stubbornly undertaken.:mad: I finally gaveup and made an appointment with my Shining Knight that I found through Service Magic! A very excellent service provided to help us neverhasbeens to find and connect with an affordable and reputable Service Repair/Contractor that can afford and has the will to care for the distraught and helpless victims of Electronic Breakdowns. Come to find out, the new transformer I put in was wired in WRONG by me. I had the Common and the 240 reversed as well as the Secondary, of the Transformer, which of course killed the new transformer. The Replacement was wired differently from the original and I was relying on the wire colors not function. The heater service breaker was also shorted! Sooo, the moral of this story is, " Save yourselves double the bucks and suffering!" Find your Local Shining Knight by going to ServiceMagic.com This project is now finished and solved. Now on to the next one. The airconditioner in my truck!:D