Ask Me Help Desk - Ac will not turn off

Last summer I think it was the evaporator coil that was replaced for a/c. I noticed then that the unit would not turn off after reaching desired temp. This summer the condenser motor outside had to be replaced. And its worse about turning off. It runs like all night. I have no if it goes off because I fall asleep. It reaches desired temp & stays on. I have to manually up the temp for it to turn off. Any suggestions. I have a honeywell digital thermostat RTH7600. I have not had any work done on downstair unit & it works fine.

You could have a bad thermostat or the ac contactor could be bad and isn't opening to stop power from passing through.

I had a second opinion. He said it could be there is too much freon or the compressor is bad because the pressure was reading 100. He didn't want to do a compressor test without knowing how much freon was in the system. When the evaporator coil was replaced that guy said he put 6 lbs. This guy removed 3lbs to see if the pressure would drop. Pressure didn't drop. He had to leave to service other calls. Next day, that company sends another guy. He does a bulb test and something else. He says that was fine. He continues with the idea that the pressure is too high. He takes out 1/2lb before trying the compressor test. He attempts the compressor test and the compressor overheats and shuts down. His supervisor tells him to start "fresh". Remove all freon and fill again. He removed freon until pressure was zero. He filled unit with 5lbs. Pressure was still 100. He had to leave because remains of hurricane Isaac was in the area and he also had other service calls. OK. Guy that replaced fan returns. Well, the fan he installed was not the correct size because the top part it is screwed to started to crack which means the fan could possible fall on top of the compressor. He wants to replace the entire condenser unit. But he wants to replace it with R410A without replacing evaporator coil. Is that smart? He said that he could purge and re-use the lines too. I don't have a warm and fuzzy about him. If he messed up a fan, imagine what he could do to the whole outside unit. What would be the best solution? Is it OK to switch to R410A or should I replace with same thing I have?

You cannot replace a r22 system with a 410a outdoor unit. The reason is 410 runs at much higher pressures and r22 is not designed for that. If you go to a 410 out door the indoor coil will also need to be changed. I honestly don't think you need a whole new system it's just the guys working on it can't figure it out and that's the easiest solution for them plus the cost of the new system.

The guys needed to check your super heat and subcooling. Subcooling lets you know how much liqued refigerant is in your evaporator coil and super heat will tell you how much freon is in your system over all. Their guages should have told them that in the first place. They should have never taken all your refrigerant out. None of them would ever come back to my house doing work like that.

Which side is reading 100 on the gauge ? r22 system should be at 40 degree coil temp and 58 to 60 psi it shouldn't be less than 56 psi on the low side. The high side should be 200 psi or could be more depending on how hot it is out side how dirty the coils are and if filters are clogged.

Quote:

Originally Posted by Terrycloth

Which side is reading 100 on the guage ? r22 system should be at 40 degree coil temp and 58 to 60 psi it shouldnt be less than 56 psi on the low side. the high side should be 200 psi or could be more depending on how hot it is out side how dirty the coils are and if filters are clogged.

The receipt has that the suction was 100 psi and the head was 200 psi. Thanks for your help.