Hayward H400idl works for a little bit, then A0 code


New member
Sep 14, 2021
Las Vegas
Pool Size
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
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!


Gold Supporter
TFP Guide
Jul 21, 2013
Northern NJ
Pool Size
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
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.


Well-known member
Mar 30, 2019
Las Vegas, NV
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.