leichter@yale-com.UUCP (Jerry Leichter) (01/31/84)
I don't know about the Pinto, but I can tell you how typical heater systems are built, and how they fail. The heart of the heating system is a heat exchanger. Air flows through the exchanger and into the car. The engine coolant - "heatant", as far as this application is concerned - may (for hot air) or may not (cool air) flow through the exchanger. The flow through the exchanger is controlled by a valve. On the ones I've seen, the valve is operated off engine vacuum through the heat control inside the car. Now, there are several places such a system can fail: The heat control inside the car my be defective, and not properly connecting the valve to vacuum. Any of the hoses bring vacuum to the control, or from the control to the valve, may have a hole or be blocked. The valve may not work. The tubes in the heat exchanger may be clogged, preventing the engine coolant from flowing through. It is usually not hard to find the appropriate parts under the hood. If any of the first three possibilities is the problem, it's easy to fix. (In the case of a hole, you would hear the vacuum leek any time that portion of pipe was under vacuum. I don't see how one of these pipes is likely to get blocked except by being crushed somehow - also easy to find. I'd bet on the valve, though. They are fairly cheap and easy to replace.) If the heat exchanger is clogged - which doesn't seen likely in a 3-4 year old car, though if you've had problems with the radiator clogging up... - you can try flushing it. If that fails, you've got problems; heat exchan- gers are often very hard to get at and replace. -- Jerry