SOME HINTS ON "DIRECT AIR" HEATER PROBLEMS.

Two heaters were offered for Corvairs. In 1960 if you wanted an optional heater the gasoline type was all that was available - it's a great heater but Chevrolet thought it had met with consumer resistance. As a result, the "direct air" heater was born. It joined the the gas heater as an option in 1961 and we think 98% of all the Corvairs had direct air heaters after that. The gas heater was discontinued as an unpopular option in 1964, while the direct air heater became the only heater until end of production in 1969.

First a description of this type of heater is in order.

The lower part of the engine is enclosed by shrouding which forms a "heater box". The idea is to trap and control the hot air that comes off the engine so it is available to heat the passenger compartment. To avoid overheating the engine two damper doors are controlled by thermostats at the back of the engine. These "fail-safe" T-stats expand when overheated (or when they fail) which pushes the door open to let excess hot air escape. Two large 4" heater hoses channel the hot air up to a heater "distribution box". Here the heat is regulated as to it's entry into the passenger compartment. A blower motor and wheel aids in forcing air. (To visualize all this see the drawings on page N3). The system works quite well as long as things are as they should be.

THE HEATER SMELLS BAD - this is, of course, the most common complaint about the Corvair direct heater. 95% of the time the smell is that of burning oil. Obviously this is caused by oil leaks in or around the "heater box". When the oil leaks it comes in contact with the manifold logs and turns to smoke, which gets pulled up by the ducting. The worst causes of these leaks will be the rocker arm cover gaskets, the pushrod o rings and the oil pan gasket, although other leaks can cause some odors too. First, the oil leaks must be replaced (see our engine section for seals and o rings). In addition the "heater box" is sealed up with what are called Shroud Gaskets. These should be installed to help prevent oil and water from entering the heater box area from the outside (this is our part # U-24).

CARBON MONOXIDE LEAKS - are not that common but can happen anytime a packing is loose or missing or there is a hole or crack in a pipe. Such leaks are very dangerous and must be repaired immediately! See our exhaust section for repair parts.

THINGS SEEM TO BE FINE BUT THERE'S NO HEAT - if the heater fan is working, but you get only cold air, then you need to check - THE 4" HOSES - make sure that they are both in place and aren't full of holes. If they need to be replaced the hose is PN U-458 and is sold by the foot. 5' will do both sides of a 61-64, 6' both sides of 65-69.

MISSING SHROUDING - if any of the lower shrouding is missing then most of the hot air will escape and not be available. We have most all shrouding available used.

BAD THERMOSTATS - when the "bellows" damper door thermostats fail they expand out, making sure that the doors open. Unfortunately in cold weather these doors usually must remain closed, even when the engine is warmed up. If they are open prematurely then the hot air will escape.

THERE'S HEAT BUT NOT MUCH VOLUME OF AIR - your air or heat control cables may be stuck or broken. See the CABLES section for replacements. Also the heater or defroster hoses may be plugged up with either loose insulation or other matter (mice love Corvairs and like to make nests in the ducting).

HI-VOLUME BLOWER MOTORS - can increase your volume of air up to 40% without major modifications to the system. This is very helpful for all Corvairs but especially vans and convertibles. The hi-volume blower motor is PN U-2488. In addition you should replace your old two piece riveted fan with a one piece plastic fan PN U-2489 (no more rattling fan!).

Remember that the Corvair direct air heater works very well when some basic things are the way they should be!