Peter,

Thanks for the response. What I meant about the heater valve is that it seems that it is preventing flow because the hose going from the valve to the firewall is not hot.

I suppose blocking it off completely would be good to ensure that this is not the problem.

It seems that there are only three basic things that can lower the vent temp; ineffective refrigeration, heat from the heater core or fresh air entering the cabin.

It seems like fresh air is the likely cause, but it would be easier to totally eliminate coolant flow to the heater core before trying to figure out anything with fresh air leaking in.

Thanks again for the reply.

Any comments or thoughts are welcome.

Have a great day,