Air Conditioning - HVAC gone crazy

http://forum.doityourself.com/showthread.php?p=994971#post994971

I made a post in the heating area as that is where the problem started. My AC isn't working now so maybe this is a more appropriate place. Any help would be appreciated. Thanks

QUOTE from other forum link "I am new to these forums and am looking for some advice. A few months back my house was struck by lightning. It damaged several electrical items in the house. About this same time my furnace started acting up. Once it was triggered by thermostat it would not shut off...It would just keep heating and heating. The only way I could get the thing to shut down was to pull the cover which released the switch. Even disconnecting the thermostats would not stop it. I've checked the wiring, fuses and circuit breakers. The diagnostic LEDs appear OK on the Two-Zone board and the furnace control board. I replaced the control board with a used one and it still did the same thing. The weather was very mild here for a long time so I ignored it. Now it is warming up so I thopught I would give the A/C a shot. The outside unit will not turn on. When I set the thermostats all the way down and replace the furnace cover the blower runs continuously. It is getting warm now and my wife is on me pretty hard. I was recently disabled so money is tight and I am trying to save some bucks. I am pretty competent with engines and computers but this is my first stab at HVAC. Any help would be greatly appreciated.

I have a Carrier Weathermaker 8000 Two-Zone system that is about 8 years old. I have a 2 story house with a digital Carrier thermostat (non-programmable) up and down. The furnace is gas-powered.

UPDATE***** The blower did shut off. I opened up the thermostats so that they were disconnected and after a while it shut off. I closed the panels and it waited for a bit and the fan blower started back up again...

UPDATE2***** I replaced both thermostats and it is acting the same" end of quote

If you are up to it lets set the thermostat to cool and fan at auto, now get out our trusty volt meter and check for 240 volts at the outside condensing unit contactor (both sides) check between L1 and L2 then check the lugs for the 24 volt control power to the electromagnet at the base of the contactor report back findings Note: this will need to be done while the power is on so dont even attempt this unless you have real good steady hands and electrical circuit checking experience, the few dollars you save by not calling a Pro are certainly not worth dying over, always weigh in the risk factor (we all know the risk factor is always there) I quess the benefit has to be weighed against it YOU DECIDE Ok disclaimer over LOL

Thanks for the reply. I will try this over the weekend and report back...

Have you replaced the zone control board? I suspect the problem, or at least part of the problem, is there.

Doug M.

I just came in to update and after I bipassed the two-zone board my A/C works fine. My brother-in-law supposedly had tested it and the LED wasn't showing an error code. Upon inspection of the board it has no evidence of damage. I guess the lightning must have zapped a component and has frozen it open or closed. The cheapest I have seen the part online is $321! I'm thinking about just leaving it bi-passed for that price. Does anyone know of a good used HVAC parts dealer?

PS Thanks for all the help!

I don't see that the Weathermaker 8000 has any type of integrated zone control. Is it a separate panel? Controlling dampers to turn the air flow off and on for the 2 zones? What brand? What type of thermostats do you have?

A new simple 2 zone controller isn't much more than $175. Unless this is a proprietary system of some sort, $321 for just the board is a bit high.

Doug M.

It is a separate conrol board that controls the dampers but it must also send commands to the main control board considering what was happening with it. It does not say Carrier on it but it says WeatherMaker which the furnace also says. I don't see that I would have to get the same brand again...in fact I don't know that I want to. Early on when we bought this house the same board freaked out in a different way and had to be replaced (under warranty fortunately). Any suggestions on other brands or places to buy? The new thermostats that I just put in are Lux programmables from Lowes. I figured I could rule out the stats that way and if it wasn't the cause I would now have programmables instead of standards...

Arg! Just found the sales doco. This system is made by Carrier and is likely proprietary. I doubt that you can use any thermostats but the ones that were there before. This may be part of your problem.

Search the internet for "HVAC zone controller" to look at possible replacements if you want to try that, but I can't promise that anything else will work with your dampers and furnace.

Bypassing the zone control will work, but only one of your thermostats will control the whole house (which may not be a major issue).

Good luck.

Doug M

You've been a great help Doug! When I replaced the stats it acted the exact same way as with the factory ones so I think they are OK. They or I mean it seems to control the sytem well when bi-passed. I have found some zone controllers on the net for about $160. In my mind I'm trying to figure out how one of these would not work. It seems to me that they all do the same thing...sending commands to heat or cool or open dampeners. The wiring blocks look like they have the same connections. I am a HVAC dummie so my mind is not so good.

Sounds like you're somewhat on top of this. If you've figured out how to bypass the zone control, you can't be that dumb. Just make sure any zone controller you consider is capable of controlling the 2 stage Weathermaker 8000 furnace. Not all can handle 2 stage heat.

Doug M.

I've definitely learned a lot in this process. Thanks again for your help! I going to leave it bipassed unless the wife doesn't like it ;-)