House AC unit turns on but indoor fan does not

TomC

TomC

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Weird that I post these types of Q's here but I've always had good knowledgeable responses from the folks here...

A few days ago it was pretty hot so I fired up the AC for my home

- Outdoor AC unit appears to work fine
- Indoor blower fan works fine on both auto/on with heat on, heat off, but not AC on

...so when AC is on, indoor blower fan does not come on either with the fan at the auto or on position


All the major individual components seem to work independently properly, just not together, any idea why?
 
Please understand that, as a Floridian, I know the value of air conditioning.
A few years ago, my wife reported that she was feeling warm, so I studied the situation.

Same as you: A/C unit consumes power, but the fan does not send the cool air into the house.

I studied the situation, and perceived several things:

The chiller was working just fine, because there was a big lump of ice covering the place where cold air was supposed to be manufactured. The fan was never turning on, so the warm air in the house was just getting warmer. I figured that some circuitry was not telling the fan to turn on, so I looked for a place to send power to the fan, and I found it! I used a piece of wire with alligator clips on each end, and clipped one to power and the other to the terminal that energized the fan.

WHOOSH, and cool air entered our home, ending the immediate problem.

I called an air conditioner repair service, and requested non-urgent service, which is far cheaper than FIX-IT-NOW! A few days later, someone called to fix the problem, and replaced a $75 module, plus $75 more for the service call. It is no treat to spend $150 to fix an air conditioner, but emergency service is far more costly.

So please exercise your head-bone when some sort of problem arises, and try to
produce a solution that addresses the immediate issue without incurring enormous expense.

As motorcyclists, we often encounter situations where careful thought can aid a solution to a problem.

Good luck!
 
Sounds like the control board, located in bottom of furnace. Usually a Honeywell. I'm on my 3rd in 12 years. I buy them online, do a simple wire swap and back in action.
 
DJM said:
Sounds like the control board, located in bottom of furnace. Usually a Honeywell. I'm on my 3rd in 12 years. I buy them online, do a simple wire swap and back in action.
Click to expand...
wow nice guess! im on my 2nd one in 4 years lol, was hoping not to have to resort to replacing it again however.
 
What makes those boards (they are pretty simple no?) go bad almost as frequently as Leafs missing playoffs??

Cheap, not well designed?
 
mxs said:
What makes those boards (they are pretty simple no?) go bad almost as frequently as Leafs missing playoffs??

Cheap, not well designed?
Click to expand...

only anecdotal but after we installed a "whole house" surge protector our HVAC controls have been more reliable
 
Definitely the control module, they tend to fail because electronic circuits don't like heat, humidity and dirt/dust, all of which you will find in a furnace. You should never have to replace one every year or two. Before you replace it, look for clues as to the cause. It may be as simple as faulty relay, but in 17 years of service work I've found the usual suspect to be water leaking from above the blower compartment. Look for obvious signs of leakage, you should clean furnace and a/c drain lines yearly to prevent blockage and overflow.


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