coleman presidential model #7966A856..........

[Guest]

Turned the a/c on for the first time sunday and all ran well. Tried to turn it back on Mon. and the fan will not start talking about the fan to the squirrel cage. Getting nothing, turned it back to heat on the front of the furnace and fan wont come on then either. Tried to get the fan to run using the fan auto and on switch on the front of the furnace and nothing. Any ideas?

The whole unit outside and inside will not kick on. Will be glad to give more details as needed!!

Thanks in advance for the help!!!!

[wes]

the fan doesn't run in contiouous/manual mode?

[Guest]

Tried to get the fan to run using the fan auto and on switch on the front of the furnace and nothing. Any ideas?

No it does not.

[wes]

next is to check if power is getting to the motor and if not check the high limit switch, the motor capacitor and the thermostat

[hvac1000]

Also check for 24 volts at the transformer. If you have 24 volts there you might check the low voltage wiring. It sounds like the A/C fan relay might be bad.

One last thing. There is a high limit control in the furnace that has a red push button. Turn off the power and push the red button in the center of the control. Usually this control only works the furnace but I have seen them shut off the 24 volts to the controls.

[Robert]

This is most likely a blown transformer or faulty main breaker for nothing to be working.

Open up the a/c control box and see if you have 24V power coming from Secondary side of transformer.

Also, check service panel to ensure all breakers are on for Furnace.

Thanks,
Robert

[Guest]

here are some pics of furnace if it will help diagnose the problem, have went to a few hvac supply houses here and none of them have parts for this furnace.

[Guest]

all breakers are on, not sure where to check the transformer and which with setting on multi meter to check them with.

[Robert]

Hi,

Your transformer will say Primary 120V and Secondary 24V.

You set meter to test at setting above but closest to 24 VAC, like 200VAC for example.

It has to be above 24, so the number closest, but above 24 VAC.

On the 24V secondary side will be two terminals or more across from each other.

Place one lead on each at same time to test for 24-28vac.


IF you have it reply back.

IF you do not have it, go to other primary side . Change meter to test for above , but closest to 120VAC and test those the same way for 120-123 VAC.


Either your low or main voltage has been interrupted. Since breakers are on or ~appear~ to be on, they need tested also.


Could be a mouse has chewed through a wire. You test the circuit wires to find break.

This can be dangerous if unfamiliar with electrical troubleshooting and crossing up wrong wires when testing can cause costly repairs.

May be time to call a Tech if not found easily and soon.


Take care and best wishes,
Robert

[Guest]

from the pics where exactly is the tranformer located? It isnt in the top box, is it in the bottom box?

[Robert]

Hi, It should be in top box for a/c and one in bottom box for heat or could have one in top or bottom for both.

It will most likely be a 40VA transformer.

It looks like it behind the wires to the far left of opened top box.

Can you move the wires for better view ?

Thanks,
Robert

[Guest]

thanks robert found the transformer, it is in the lower box, along with the fan switch and lower limit.

Checked and got 28 vac to lo side, and 123 vac on high side of transformer. checked fan switch and got 122 vac at fan switch, and showing 0 vac at the lower limit.

I greatly appreciate all of the help!!! Sorry it took so long to get back to u guys about this, have been helping friends and family move their belongings. Sitting here in st. joe, mo waiting for the mighty missouri to crest over its banks, looking to flood here. Sucks!!!

[Guest]

I also turned off power to the unit, and checked continuity at the switches using ohms setting on multimeter. at the lo limit it zero's out, the fan switch shows a reading of 0.001 to 0.007, the lo side and hi side of transformer also zero out.

[Robert]

Hi,

How many wires connect at t-stat ? What VA (voltamp) is that transformer ? Look on side for VA rating.

Thanks,
Robert

[Guest]

2 wires at t-stat, 15 va on transformer.