I had a new ac built to order that replaced my old one 3 years ago. Right after warranty was off (2 years in) a/c started to act wierd. During winters from time to time, it starts to blow cold air and with no reason goes back to normal. During summer, all is ok though. This year again same thing happened. I manually overrided actuator to open position few times. After sometime spring inside it broke, so i bought new unit (erie ag13b020) and replaced whole head, hoping that problem will disappear. After 24h however, problem came back. During the day a/c blows hot air, stops automatically and starts right back working all good, but at night though set unchanged to 80 degrees, will start blowing cold air continiously. Only way to get hot air, is again manually opening water walve, which again will make it work great during the day, but fails at night though untouched. What seems to be the problem? Also what's that part on the pripe near erie looking like oversize "watch" battery seen on last picture? Can it be responsible for the on and off cold air?



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Welcome to the forums.

I approved your post but I have no idea what I'm looking at. No makes no model numbers.
Wet heating and A/C ?

We have to know exactly what you have there if we're going to be able to help you.

That round part is a temperature sensor.

 

I will post more pictures of whole model, just quick question.
Could the temperature sensor (round thing) be the problem alone? Should it be connected with one of the cables, with the actuator directly (erie ag13b020)? I think now it's connected only with the thermostat. Also, on which pipe should it be placed on? In front of actuator on pipe that it sits on (opening valve is on), or other pipe (I have 2 pipes delivering water to the coils, picture coming), or behind?

thanks again

 

Here's the whole thing, built to order, used erie valve and TAC thermostat

 

I have a feeling the temperature sensor might be the issue. I found old picture on the net showing how to attach sensor, and it shows attaching it to the motor of actuator first and later blower. Mine seems to be attach straight to blower but I don't know.

 

A/c unit built plan. Thermostat used in is tac erie t155 series, works with
ERIE AG13B020 NORMALLY CLOSED ACTUATOR, ON/OFF, 120V and temperature sensor

 

What we're looking at is a form of PTAC.... basically just an air handler that works on chilled or heated water. Normally the lines are set up for heat or cold..... not both at the same time.

It sounds like your system is not keeping the water loop open. Either a zone valve problem or electrical problem. You mentioned opening the valve manually. If that works then you need to be checking the voltage to the valve. The temperature sensor probably locks the blower off if the water line gets cold.

 

yes, I think this is the problem but how to repair it? I just changed the actuator to new one but problem persists. I am thinking of putting the new changeover switch that measures temperature.

The funny part about this unit is, that during rest of the year it works great. Only during winters, seems to fail, and that also occasionally.
When I force the valve open, it stays open and even thermostat is working (means will switch itself on and off automatically after reaching certain temperature). After some time level is released and also works with thermostat opening and closing valve. More frequent however, especially during the nights, the level in actuator won't move back and forth, will stay in closed positing and again have to be manually forced into open.

 

You need to find out if your valve is getting the voltage required to make it move and it's not.
or... it's not getting the voltage to operate.

You need to determine if you have an electrical problem or a valve problem. If the voltage is at the valve and it wont open....the valve is bad.

If you only have problems in the heating mode.... make sure the valve is rated for the temperature of your hot water.

 

Thank you, will try that I do appreciate your time and guidance!