The Blower motor on my AC unit turns off at random times while the outside unit continues to run which is causing the coil to freeze up. The blower won't come on for 30-45 minutes after the AC has been turned off, but after that it seems to turn back on fine. I have been trying to track the problem down for the last couple months, but it literally only happens every 2 or 3 weeks. Last night it stopped again and I tried to just turn the fan (from the thermostat) on without luck. I took a look at the blower and it seemed to turn just fine. I put my hand on the back of the fan motor and it wasn't hot to the touch. About 45 minutes after it turned off the blower came back and it was working normally. What could be causing this problem? I ended up calling a buddy of mine who is an HVAC tech and he pointed me in the right direction to check the fan wire on the back of the thermostat. I checked the wire and it was just hanging in the terminal. I'm pretty sure that was the cause of the problem.

It makes sense because there wasn't anything wrong with the blower motor itself. The fan wire on the thermostat was in fact the problem. I fixed the connection and it has worked fine for the last 3 years. I have a ruud rheem heat pump, I had this same issue. The unit was installed in 2006. After going through the typical steps of checking air filters and electrical components on the unit, I found the wiring from the thermostat for the blower control to the control board was rusted in the wire nut. I cut the wires and stripped them back and reconnected the wires and the AC unit is running with out any trouble now. Remember to keep it simple. HVAC service companies love these type of calls that an experienced tech can track down quickly. If you have a basic understanding of how circuits work you can fix this easily and save a bunch of cash. My central AC unit decided to stop on the hottest day of the year. It would start and run normally for a few minutes and then the blower would shut off.

After checking the breakers, thermostat and overflow shut off (did not have one) I saw something about a blower motor capacitor. This was easy to get to and replace and my last hope before waiting for someone to come fix it. how much is a 5 ton air conditioning unitThe capacitor cost $4.04 with tax and had my AC working again. portable ac units for trucksNeedless to say I was beyond happy. air conditioning units for log cabinsI hope this can help others with a similar problem. Check your drain lines for water run off. Make sure they are clear and then check the float for the excess water shut down reset them Also check your ground. I just ran across an intermittent blower issue (cycling on and off constantly during call for heat from the thermostat) that was due to a poor ground connection on my 120 volt to 24 volt transformer on an old Janitrol furnace.

The ground side of the 24 volt half of the transformer had 2 wires connected to it. The good one went to the mounting screw of the transformer. The bad wire went to the circuit board. It was bent over perpendicular just above the connecter, and many of the strands were broken. There was also some minor corrosion. Replacing these ground connections resulted in satisfactory operation. This was difficult to troubleshoot because operation was okay if the air filter was not in place, and the issue showed up only when an air filter was installed on the supply side (dirty or clean filters both had the intermittent problem). Thank you for asking. Your thermostat 24V wire line is lose, interrupted, broken or oxidized. Solution : disconnect old 24V line, and run new line, if this restores your blower motor function the old one was defective. Thank you and have a nice day.Dometic RV Rooftop Air Conditioning Models: 457915.70X, 640312.80X, 457915.71X, 640312.83X, B57915.71X, 640312C35X, 459516.70X, 640312C85X, 459516.71X, 640315.80X, B59516.71X, 640315.83X, 540315.70X, 640315.84X, 540315.71X, 640315C35X, 540316.70X, 640315C85X, 540316.71X

Question: The fan in my unit seems to always be on. Answer: The simple answer is yes. For overall best results: The blower runs continuously to circulate air and maintain an even temperature. The compressor will come on as cooling is required to maintain the selected temperature level. Wait at least 2 minutes before restarting the compressor when it has been manually cycled off with either the selector switch or the temperature set lever. Otherwise, compressor will quick-cycle and could result in compressor or supply circuit overload. Question: My unit has the Electric Heater Option, but when it gets colder outside it doesn’t seem to maintain the temperature. Answer: The heat mode of operation will NOT replace a furnace for heating the RV in cold weather. The intent is to remove the chill on cool days or mornings. For best results when using your Electric Heater Option: Question: What should I do to make sure my filter is clean for maximum efficiency? Answer: Periodically (a minimum of every 2 weeks of operation), remove the return air filter located behind the return air grille and wash it with soap and warm water, let dry and then reinstall.

NEVER run unit without return air filter in place. This will plug the unit evaporator coil with dirt and may substantially degrade the performance of the unit over time. Question: What should I do when I notice frost forming on the cooling coil? Answer: Frost on a small portion of the coil is not unusual. Under certain conditions, ice may form on the evaporator coil. This is indicated by very cold output at very low air speed and the icing can be seen through the air inlet hole with the filter removed. Question: What steps can I take when it’s really hot outside and the A/C just can’t keep up? Answer: The ability of this air conditioner to maintain the desired inside temperature depends on the heat gain of the RV. Some preventive measures taken by the occupants of the RV can reduce the heat gain and improve the performance of the air conditioner. During extremely high outdoor temperatures, the heat gain of the vehicle may be reduced by: Operation on High Fan/Cooling mode will give optimum or maximum efficiency in high humidity or high outside temperatures.