blower won't stop and MORE! part 1

[orangecat]

1.problem similar to others but more background and more problems.
bought a pre-owned home in '04, built in '01. previous owners allegedly locked children in bedroom with return air, they passed the time by ripping up newspapers and put the strips into the return air. would occasionally hear the drip, drip, drip, had A/C man come out and fix, water in the pan problem, I think.

Fast forward to '08, A/C man, good recommendation, older man, comes out, shows me serious rust on the coil, offers me three solutions, clean coil, replace coil only, for a few hundred more, replace inside unit. I opt to replace inside unit, that was June '08. electric bills skyrocket, we never discussed efficiency, I was that guy who assumed the bills would actually go down vs. a unit with a rusted coil. gave me one year warranty, I showed him the huge increase in bills, he looks, he finds nothing. I knew he was sick, but did not know how sick. He passed away not too long after.

Somewhere in the time frame I had the issue with the unit not going off in the fall and not coming on in the summer. That contact problem was taken care of with a homeowners warranty A/C man.

Now to the present, same problem with unit not turning off, I tried both upstairs and downstairs thermostats. upstairs thermostat, if I move the selector from cool to off the outside unit will turn off. downstairs thermostat, outside would not turn off no matter what I selected.

House is a two-story 2720 sf, with a two-zone A/C. Five ton capacity. 100% electric. Here are some examples of bills..... to be continued

[orangecat]

Part II

and here are some samples of the electric bills: (I've had the same rate, 12.9 for the past three years)

1/18/08 $384
1/20/09 $580
5/16/08 $181
5/20/09 $248
9/17/07 $346
9/17/08 $466

check out this recent bill

1/22/10 $677, comparing that to the most recent winter bill with the old unit, $384, looks like at least the inside or the outside was on the entire time.

So, now I get a recommendation from a friend, she has recently had a man put a new unit in her house, he comes out, he appears to be very good. I show him outside unit, he asks what inside is calling for say I tell him nothing, interestingly enough he grabs that little pipe coming out of house, it nearly burns his hand, he says it's calling for heat. (This was a week ago, temps, in 50s or 60s no way would we have heat on intentionally)

He looks at control panel, I tell him I told previous A/C man about the control panel being installed upside down, previous man said it didn't matter. Here's the good part. I had noticed that red light on. A/C man says that red light on meant the emergency heat strips had been on for only God knows how long. Possibly since June '08!!!??

So, he thinks he might have the problem solved, but he does offer some advice, he told me to watch the control panel, it might not be good. I just tested the A/C for the first time, the outside unit wouldn't turn off, this was after he left. He was here four days ago.

Questions 1. So, does that validate the idea of the control panel being bad?
2. Does the fact that the contacts had to be replaced twice give credence to the idea that the control panel is bad?
3. What other possibilities could there be other than the control panel being bad.

[orangecat]

chirp, chirp, (crickets), anybody awake here. I think almost all of the views have been mine. Oh, well, thanks.

[HayZee518]

you mention two sets of contacts burned up. to me that indicates over current. what's causing the over current or is the contactor of choice under rated for the current draw?
from what I deduced, this is a sequential heating unit. the fan comes on after the first heating element turns on.

[orangecat]

ummm, you're way beyond me with that, but I have my newest a/c tech coming Saturday afternoon. I will ask him to consider this. I do know he looked like he checked the amount of electricity going to the outside unit.

[HayZee518]

Amount of electricity to outside unit???? The amount of current is only limited to what the unit's breaker and wire size is rated at. Theorietically you can draw many thousands of amps through a device.
Contacts don't burn up unless they are under-rated, draw many times its rated current, are forced to open under a short circuit. with a shorted motor drawing current contacts can melt. other problems is the movable portion of the contactor doesn't make up tight enough into the fixed contacts causing a high resistance, excessive current and eventually burning up. contact springs are known for this.