My carrier 48GS Gas Heating / Electric Cooling unit has an error code flashing "Limit Switch Fault" and states that the Indoor Fan Motor is not running, or to ensure that the supply-air temp rise is in accordance with the range on the nameplate. My dealer states that I do not have enough return air. I have had problems with the system not supplying enough air, period, hot or cold. But I do not believe that my return air is the problem. I have added one big 8" return line on top of what the dealer installed. I believe the Indoor Fan Motor is my problem. It is a three speed fan, & is wired for high speed. Any help???
If you have had problems in the past with not enough air, I would have to say it could possibly be the return. Since the 8" run you added will only draw 220 cfm, that is not really enough to say yes or no. Try to run the unit with the door off and see what happens.
I tried running the unit with the door off & it did not increase the air flow into the house. With the motor running on high speed, I've been told it should be moving air very good. So, I just wonder if maybe it could be the motor to the fan. It doesn't make any strange noises, but at this point I'm not sure what to do. My one year warranty runs out in April, & my dealer insists nothing is wrong & hasn't done anything to remedy my problem.
The only way you can check your blower motor is to put an amp meter on the common wire to see if anything is abnormal. Motor may be overheating, causing temporary stoppage and thus giving you the reading of a limit switch fault. Can you give me the complete model and ser #? Do you have A/C? Also count the # of supply runs to your rooms in the basement if you can. I will get the literature on this piece of equipment and get back to you.
Thanx for your reply & help. It is a Carrier 48GS018-060 Single Package Gas Heating/Electric Cooling Unit. To give you more indepth detail, and this does not make any sense to me, I have realized that when I used my gas fire place my Carrier gave me problems. After shutting off my fire place and going to bed, I would wake up several hours later freezing. The Carrier would be running but blowing cold air. I could not turn the system off at the thermostate. The fan would keep running and pumping cool air in the house. I would have to trip the breaker & set it back up, which would stop the fan but the Carrier still would not function properly. After opening the front cover of the unit, I noticed that the LED was flashing twice, indicating a "Limit Switch Fault". The Troubleshooting Guide states that the High Temperature Limit Switch is open, and to "Check the operation of the indoor (evaporator) fan motor. Also ensure that the supply-air temperature rise is in accordance with the range on the unit nameplate." I could remove one of the wires to the Limit Switch & reconnect it & the Carrier would ignite & get a gas flame. But what I don't understand is that three times this has happened when I used my gas fireplace for a few hours & then turned it off. As for the number of returns, I have seven 8-inch returns & ten 6-inch supply ducts. My dealer said I do not have enough return air & he wants to install one large central return in the floor or wall, but I have hard wood floors & did not want him to cut a large hole in the floor for a return. If you need any more info, I will do my best to supply it for you. Thanx, Bob
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