princej

carefully follow the lines to the heater core.

check for kinks or a line that fell from its mounting bracket. my dealer claimed to have replaced my lines with shorter ones and re did the hoes paths. and yes, the heater core is higher than it should be.

i have full heat since that repair about 4 years ago.

kcarlen

Thanks for the replies!

The tubes that originate from the waterpump area transition from hose to black steel tubing, and they are pre-bent to follow the engine. The only transition to the heater core is at the quick connects from my memory.

What I did find is that the overflow piping was clamped in between the crosspipe (pipe that the reservoir tank is fixed to). By removing the hose that was clamped, I am noticing that it is still deformed/damaged, and is not returning to normal shape. I will replace this chunk of hose in hopes that it provides a clear run to the reservoir.

Maybe this is causing a condition that the overflow is not working?

garrreee

I have little to no heat while idling, and lots of heat when rev engine over 1000rpm. I have also been on the highway at 80 mph with the fan on high blowing warm air, then suddenly start blowing extremely cold air. I have had the fan blowing warm air, and as it got too hot I turned the temp dial to get cooler air, but I could only get hot air.

elgremio

Hi.

I have almost the same issue (Uplander 2007 LS). No heat at all on idle, and sometimes no heat on high RPM (but sometimes there is heat).

Last year I had a problem with the radiator cap and I bought at my nearest dealer a cap but when changing I realized that the new cap was 18PSI and the old one was 16PSI.

I put on the 18PSI for a couple of day (meanwhile I was trying to get the 16PSI from another dealer) and the heat issue went away. Then, when I got the 16PSI and replaced the 18PSI, the heat issue came again.

I think the extra pressure of the 18PSI cap makes the system to put the right amount of heated coolant on the heater core, but I was afraid to keep that way because I'm not sure if the extra pressure could damage something.

Anyone knows the right pressure cap? 15 PSI? 16 PSI? 18 PSI?
Anyone could advise me what could happen if I put the 18 PSI one (the winter is coming and I want to have heater on my Uplander)

Thanks.

Papa Bear

Is the level in your coolant reservoir the correct level?

What do you mean "Last year I had a problem with the radiator cap" .. what kind of problem?

Has the coolant in your van been drained & refilled with fresh coolant?

I suspect you have some air in your system causing no heat at idle.

elgremio

Thanks for your response Papa Bear.

Last year I removed the radiator cap to watch the coolant level there (to see if there was some air traped). That cap was deformed and when putting again it started to leak, so I had to put a new one.

I think that the Uplander had never been flushed and refilled.

Do you know the right PSI cap for this van? I found mixed information around.

Thanks.

Papa Bear

Looks like 18 psi to me Genuine GM 15293434 Radiator CAP 18 PSI Chevrolet Buick Pontiac Saturn RC111 | eBay

Please answer my first question. Is the reservoir the correct level? Did it ever go dry?

elgremio

Thanks Papa Bear.

The reservoir level is correct and doesn't seem to loose any coolant (we doesn't have to refill it never).

sambo43616

our original cap was a 18psi it was leaking we put on a new one and we have had heat ever since after years of trying to find out why it was not heating at idle.
also have your gaskets checked for leaks. last june we were in Chicago and our van started over heating. We had to leave it there for them to replace a couple of gaskets . and now the heat works great.

tk1105

We started having this problem last winter, talked to several mechanics and no one seems to know what the problem is.