2005 Venture Heater not working

I have a 05 Venture that takes 30-45 min to heat up. I have taken it to a couple of dealers and they say “After we ran it for 45 min it was fine.” Do these vans just take that long to heat up? Where should I start?

Has the thermostat been changed?

Start by having your cooling system serviced and thermostat replaced. Also have the operation of the cooling fans checked, and have someone check the actual coolant temp as the van’s heats up to rule out an interior problem with the ductwork.

Often a lack of heat is the result of a failing heater core. This is more true in aging cars than in fairly new cars such as yours, but it is not out of the question.
The coolant needs to be changed according to schedule, and this is often overlooked. So, was it overlooked?
If not, do you know if the fluid was replaced with the heat on, so that the heater core’s fluid was changed at the same time?
If the system was flushed, again, was the heat on (so that the heater core was included), and how long did the flush take. In your car the minimum time to flush the system is close to one hour. Did it take that long?
Go back over your maintenance records or just memory. Assuming the thermostat has been replaced, it is likely the heater core portion of the cooling system is just mucked up.
You may be able to get this part of the system cleaned out and working properly. I would visit a coolant expert rather than hope that even the dealer is going to do this right.

"The coolant needs to be changed according to schedule, and this is often overlooked. So, was it overlooked?

Hmmmm…a 5 yr old GM vehicle. Probably on DexCool - probably a giant label somewhere that says 5yrs/150K miles. I’ll bet its not been serviced because of following the schedule…and the problems are starting. I know some have said its fine, but that GM DexCool stuff & long intervals was a terrible mistake - at least from the pt of view of the consumer.

Yes the thermostate has been changed (2x). This issue not new and has been going on since we got the van in summer of 2005 (bought used). Three different mechanics have looked at it and have found ‘no problems’. I believe the last time the cooling system was flushed.

In terms of the system being flushed, I do not know if they flushed with the heater on or how long it took. I have new mechanic so I was going to have him look at it (done with the dealers…it was under warranty so I was having them do the work).