Hayward H400idl works for a little bit, then A0 code

[EdwardR]

Hey all,

I have a Hayward H400 idl heater that came with the house, I've been here for about 8 years, but I'm guessing that it is probably 15-20 years old.

It fires up and runs ok, for a little while. Then, the blower motor stops and it shows an A0 code. If I reset it, the blower will not come back on and the A0 code returns. However, if I wait for a little bit for the unit to cool down, then it starts working again for a little bit.

I understand that the A0 code is the vacuum switch to sense of the blower is running, and that the blower should come on first. I'm wondering if there is a thermal overload switch, or if something is going bad and quits working once it gets hot?

Has anyone else run into this? Any ideas to help troubleshoot would be appreciated!

 

[ajw22]

Welcome to TFP.

Have you opened up the heater and looked at the condition of it inside?

Look for signs of rodents nesting in the heater.

Post pics of what it looks like inside.

 

[swamprat69]

Yes, the blower motor does have an internal thermal overload. It could be something as inexpensive as a weak or open run capacitor for the motor or it could be a problem with the motor itself. You can check the capacitor with a multimeter capable of reading microfarads (uf), with the power off and one capacitor lead disconnected.

 

[EdwardR]

Ok.. took me a little while to get back to it. I took a look inside. I did not see any animal nests, but found something else. I took off the top and disassembled down to the heat exchanger. It looks rough.

I'm thinking that might be a problem. I tried straightening out the fins on the heat exchanger at the bottom and it actually seems to have helped. I'm thinking that might have to be replaced though. Would that cause this issue?

 

[swamprat69]

Looks like some of the damage may have been caused by a misalignment of the heat exchange. Should not be enough to cause AO problem. It wouldn't hurt to have the whole heater cleaned and checked. Screws missing from gas valve support bracket? Should still check blower motor capacitor and blower motor running amps. Also remove and clean burners and orifices while checking the underside of the heat exchanger for any blockages. Clean the flame sensor. Then you will have a better idea regarding the condition of the heater. I have a 16 year old H400idl that is still chugging along, but I had to replace the ignitor this year and also removed and cleaned the burners and orifices and flame sensor and inspected the heat exchanger as long as I was in there.

 

[ps0303]

Ok.. took me a little while to get back to it. I took a look inside. I did not see any animal nests, but found something else. I took off the top and disassembled down to the heat exchanger. It looks rough.

I'm thinking that might be a problem. I tried straightening out the fins on the heat exchanger at the bottom and it actually seems to have helped. I'm thinking that might have to be replaced though. Would that cause this issue?

It's time for a new heater. The heat exchanger looks like that because the unit ran and overheated it. Probably some blockage in the burners. But at this point, it's really time for a new unit. Don't waste any more energy or time on it.