Water Damage Fan Runs But No Heat

IfMineItBr8k

I'm sorry in advance for the length of this post, but I want to be concise. I am trying to sell a house "as is" but stated I would make sure the heat was working properly. Because the house is selling cheap I cannot put too much $ into unit. The house has been unoccupied since last fall. Prior to that there was a broken pipe that caused the crawlspace to flood affecting the airhandler in the crawlspace. The water was evacuated and a service tech came out to look at the unit. Unit checked OK and was in service about 2 months before problems started. Heat would come on but would not shut off. Had to turn off breaker to get heat to shutdown. Turn on breaker and would work a few days. Tech came out and replaced transformer. Unit worked for a week then the fan would not cutoff and the heat stopped working. Tech came out and replaced sequencer. Worked for a day then the same problem. The sequencer was pulled from an unistalled unit in my garage that is a 1.5 ton 10seer upflow Comfortmaker and placed in the 2.5 ton 10seer horizontal flow airhandler (by Tech's OK). With disconnected power I went under the house and cleaned all the contacts of any rust and corrosion with contact cleaner and a softwire brush. The only parts that appeared affected by the water were toward the bottom of the unit. That included the transformer (which was replaced) and what looks like a switched replay. The relay is in bad shape as are the paddle connections, but nothing looks shorted or burnt, just rust causing poor contacts. I am going to replace the paddle conns and the relay, but the man/model# tag is missing. The old relay was a completely enclosed small black box with five connections having 4 occupied with wires. I documented the connections and tried to find a replacement. While getting a new part a Tech suggested a repacement (White-Rodgers 90-340) that has many more connections and an exposed coil. I disassembled the old part and have a good idea of how the switch is controlled, but am unsure of how the wires should reconnect to the new part. Both parts have numbered terminals, but I am unsure if this numbering system is universal and I can just reconnect the wires to the corresponding number. I also wanted advice on whether or not I should put the old sequencer back in seeing how it did not solve the problem and any other recommended service I can do while the power is down and I'm under the house. Everything I own breaks so I do have experience reparing things. This past year I did fix my Trane Compressor unit just using some common sense and little research. Thanks for any help you can provide and in exchange I'll give you some tips on what not to do when tiling floors.

Thanks,
Mike

btophat00

always install fuses on both legs of t-former. these usually dont go bad. probably have short in system. look at the back of the circuit board.

NickTech

unless you have electric heat, there aren't any "sequencers" in a furnace. how old is the furnace and what is the model #. like i've posted before, in a furnace with a computer module moisture is like preforming a labotamy. moisture will affect the modules in different ways. it kind of sounds like you are working with a r8222 general purpose relay.(i think) there should be schematic printed on the face of the relay with the terminals. let me know what you have or maybe send a pic of the controls and i'll try to help you out.

IfMineItBr8k

I dug through some paperwork that was in the garage and found the wiring diagram for the unit. Apparently when the Tech from Sears came out he never even looked at the relay but jumped straight to the sequencer. He replaced the sequencer and said he was done. When I called Sears back out the following day because of the same problem, the same Tech came to the house and told me I should just replace the unit and they would refund the charge for the original service call. He didn't want to go back under the house. Yesterday I went back under the house, followed the wiring diagram and found out the Tech did not reconnect the lead from the relay to the sequencer and wired the sequencer incorrectly. I replaced the relay, reconnected the relay to the sequencer, returned the original sequencer back to the unit and rewired the sequencer according to the diagram and wouldn't you know I got heat and air. I called the tenants first thing this morning and they say everything is still working.

NickTech

well that was your first mistake, calling sears. i'd get them to refund your money and then i'd charge him for wasting your time