No heat!

I have a '98 Dodge Carivan with 160K miles. It runs great with one exception. No heat, and I live in central WI and it’s January…

I’ve had it in the shop a few times and each time they have “fixed” it, but I haven’t felt heat since September.

I trust the shop and they haven’t charged me for the work, but it is more of a mom and pop shop. The water pump is new and the thermostat was recently replaced. Could this be a computer issue like my stepfather suggests, or do I need to look someplace else.

You may have a plugged heater core. Feel the hoses going into and out of the heater core. If one is hot and the other is stone cold, the core could be blocked. Sometimies it is possible to reverse flush the heater core to get the junk out.

Another possibility is that there is air in the cooling system. Air can sometimes be bled from the cooling system be starting the engine with the radiator cap off and letting the engine run until it is fully warmed up.

The easiest thing to try would be to flush the heater core. This is fairly easy to do with a garden hose, which most shops have inside. If this has been tried with no success, and there is plenty of coolant in the system, it may be a blend door problem. The only way it could be a computer problem would be if your van has electronic climate control and the module for that has gone bad.

I’ve had it in the shop

No, you had it in a shop not the shop.  You need a different shop.  Note there is no requirement to use a dealer as your shop.  

    Dealers are no better (or worse) than independent mechanics for almost anything you might need done on your car.  They will almost always charge more per hour and often more for parts and supplies.  They also tend to look at repairs a little different than the independent. 

A dealer may well recommend work that strictly may not be needed, but could be connected to the problem or maybe replace a part when a little repair would fix it ALMOST as good a new.  

There is no need to bring your car to the dealer for any service other than service that is going to be paid for by a recall or original warrantee.  During the warranty period be sure to have all required (as listed in the owner's manual) maintenance done and to document all maintenance work.

I suggest that most people would be better off finding a good independent (Not working for a chain) mechanic. 

Note: Never ever use a quick oil change place. They are fast cheap and very very bad.

There really are only a few, easily checked reasons for your heat problem. First, is the engine getting up to operating temperature? Check your temp gauge or open the hood and carefully check the top radiator hose to see if it’s hot if you don’t have a gauge.

Coolant is not circulating through the heater core. Easiest way to check is by turning on the heat full on and feeling both hoses that go to the core. They will be on the passenger side firewall. If one is not hot, the core is pluggedor their is air in the system. If both area not hot, check valve may be stuck shut if there is one or you’re seriously low on coolant.

The blend door is stuck on cold inlet position. Could be door motor or something fell into ducts and is blocking door movement.

Fan is not running.

All of this assumes the system is filled. Saw that recently. Check it first!