t660 No heat

My Kenworth has no heat cab or sleeper.

Dash switch seems to work I get ice cold A/C and not so cold air on the hot side.

Checked fuses and relays all seem fine. Coolant level is full.

I did notice coolant lines on passenger side of engine are cold. No leaks to point me towards heater core.

Any ideas or suggestions on where to look next.

 

I did not see any. That was one of the first things I looked for. I had 2 on my N14

Engine is a Paccar if it makes any difference.

 

Imma have to wait until light to find that valve. I been working on it out in the parking lot.

I believe I know what valve your talking about. It's on passenger side of firewall hopefully I can either bypass it for now or get it working.

 

Finally got it fixed... Heater control valve on fire wall was plugged.

I went to take it off and black soot was all inside clogged everything up.

After cleaning everything out heat works like a charm.

I appreciate the advice on where to look