He has a slow fan and dim dash

Question:

I have a 1971 Firebird Espirit that I have owned since it was new. I have spent a lot of time restoring it and it is a great daily driver.

I had the air conditioning converted over from R12 and it cools well but the fan will not blow very hard. I had the fan replaced but it still doesn’t blow very hard. It blows on all four speeds of the controller but it just blows very slowly, even on high.

The air conditioning shop where I had the conversion done has gone over everything and even replaced the seals on the ductwork, but they also are stumped as to how to get the fan to blow more powerfully.

Also, all of the lights in my dash work but they are all somewhat dim, even when adjusted to the highest level. What do I need to do to address this issue?

Answer:

As far as the fan is concerned, your diagnosis should begin with a determination as to whether there is an electrical or mechanical problem that is preventing the motor from spinning fast enough, or whether there is an obstruction or other issue that’s preventing the full force of the fan from reaching the air outlets in the car.

Use a meter to measure how much voltage is actually reaching the motor with the fan switch in each position. It should receive full voltage with the switch in the high position.

If the motor is receiving full voltage and spinning as it should, then take a look at the air delivery system.

One area that is often problematic is the system of actuators and door flaps that determine the path the air takes in the HVAC system.

If the actuators/doors are not moving freely and in the correct sequence, you may perceive that the fan motor is not doing its job. Another possible culprit is an obstruction in the exchange box or ductwork. Unfortunately, the only way to investigate for this is to start taking the system apart.

Your dim dash bulbs are likely due to yellowed, tired bulbs and/or excessive resistance in the circuit, typically caused by corrosion in the switch or harness connectors. Whenever I had a dash out for repair I’d automatically replace all of the bulbs if they were not relatively new because over a span of many years the bulbs yellow and get dim. Check the cleanliness and security of underdash wire harness connections and grounds. If the problem persists and you feel ambitious, change all of the bulbs and see what that does for you. If the light is still dim replace the light switch.