carrier rtu economiser

[HvAckid82]

Hey guys,
I have a Carrier rtu M# 48TJF01658AQ S# 2401F90581. Ok my problem is the economiser. I was called out to a job just to make sure the unit was working ok, and it wasn't, and when i got there the compressors where running and it was 45* outside. So with that temp and the setup i know there was a problem. Well i found that the economiser control (which is white in color) was flashing 7 times and that means "return air sensor problem". Well carrier said they never heard of this. Carrier says they have mixed air sensors, discharge sensors and outdoor sensors on this economiser. They think I am nuts but on the control it states " 7 green flashes is return air sensor". I ohmed out the "return air sensor" and got nothing so i know its bad. Does anyone know what I am talking about? And are all of the economiser sensors/thermistors 10,000ohms? If anyone has part numbers that would be greatly appreciated too. Thanks
Chris

[jrbenny]

How do they plan to use differential dry bulb changeover without a return air sensor? :rolleyes:

I don't have access to the old part numbers, but they exist.

Here are the current sensors (http://www.docs.hvacpartners.com/idc/groups/public/documents/techlit/48_50h,p-21si.pdf). I don't think they are the same as the old one.

[airdata870]

do you know which controller it is,novar,penn johnson or a premier link? i think the penn johnson is the only one with code 7, does the controller have 4 potentiometer dials, a status led and a config. button?

[Dallas Duster]

Hey kid your missing a letter or number in your M# and I believe you have a johnson controller and a johnson actuator. Actually missing a few letters or numbers

[HvAckid82]

I wasn't able to find any more info/numbers on the unit. The controller does have a green led light/status light and has four dials on it maybe it is the Penn controller?

[airdata870]

I wasn't able to find any more info/numbers on the unit. The controller does have a green led light/status light and has four dials on it maybe it is the Penn controller?

hvAc82,see if this helps.let me know