1998 Chevy Silverado Heater Control Problem: Fixed!

Your Chevy 98 Silverado has been giving you good service in and out of work. But the heater control of the car is facing some issues every now and then.

So, how can we fix the 1998 Chevy Silverado heater control problems?

Failed heater blower motor, burnt-out transistors are two of the common reasons for the problem.  Check for burnt-out transistors and replace them with transistors of the same ohm values. You might need to replace the blower motor.

This is just a rundown of what you will get to know from this article. These fixes require thorough inspection and specific procedures to follow. Lucky for you, we have got them covered!

Let us dive into this bite-sized read-

Why Is My 1998 Chevy Silverado Heater Control Having Problems?

Chevy Silverado 1998 is the perfect car for doing heavy-lifting work and is highly durable. Unfortunately, the HVAC control unit of the car might face heating issues and restrict air flows. This can make the ride slightly less enjoyable for you.

The HVAC (Heating Ventilation and Air Conditioning) problems can be fixed easily. We’ve covered two major heater control problems and their solution for your convenience.

Problem 1: Air Exiting From Floor Vents Only

Air will only exit from the floor vents due to problems in the zone/mode selection. The AC button in this case will also become inoperative. These are two of the key symptoms of many more in this case.


Despite the mode actuator motor assembly operating perfectly, the AC button will be inoperative. And so will be the case for the recirculation button and Zone/mode selection knob. The air will only exit from the floor vents for this reason. 

The fan speed button, the temperature selection knob, and the rear defroster will work as usual.

This happens due to the switched 12VDC transistor being located on the flexible circuit board. The 1998 control units have three transistors present on the board. But only one of them is involved in the +12V power problem. Regardless of the board type, the repairing process of the problematic transistor is the same.


The 1998 Chevy Silverado uses the ACDelco climate control module. This switch helps you to regulate and control the heater of the car.

All you need to do is replace the burnt transistors with transistors having identical ohm values. You should replace the N724/2857 with an MPSA56 transistor. Using an MPS2907A can also work well as a substitute. 

You can also replace older ACDelco models with a 2N4403 version, a most recently manufactured version. But this is purely optional and not required as they are unrelated to the symptoms.

Remember that the repairing procedure only applies to ACDelco climate control module units for chevy 96-98. 

The transistor might keep blowing after replacement if too much current passes through it. A short to ground in the circuit can be blamed for this. The transistor involved is rated at 500mA at 12V DC. 

Follow the light green wire from the control unit harness to the cycling switch. The cycling switch should be on the side of the AC accumulator. Diagnose both of them separately. 

You have to fix this short circuit. Bridging the transistor connection without fixing the short circuit will allow it to damage the VCM.

Problem 2: Damaged / Failed Blower Motor Resistor

The entire heating system and air condition can be affected by a failed blower motor resistor.

It’s an electric component that belongs to the air conditioning and heating system of the car. The blower motor’s fan speed is regulated by the resistor. 

Frequent adjustment of fan speed settings puts constant stress on the blower motor resistor. As a result, the resistor can end up failing eventually after a while.

You will face the symptoms below if you have a failed blower motor resistor-


  • Blower motor only operates at 1 or 2 speeds instead of 4 speeds.
  • The Blower motor is not functioning (no air from vents).
  • The blower motor does not work in certain settings

It’s highly likely that your blower motor has failed if you detect any given symptom. In case, your motor blower needed a replacement, we’ve a list of the top products for you-


The only solution to this issue is to replace the blower motor resistor. Replacing the blower motor resistor costs somewhere between $44 to $55. An additional $70 will be cut from your budget for labor costs. 

So it’s safe to assume that the total cost can end up somewhere around $114 and $125.

But, don’t start counting the dollar bills yet! You can even fix up the blower motor resistor at home within an hour! And you do not need to be a professional to do so. This will save you the money that you were initially going to spend after labor costs.

Follow the given instructions to replace the blower motor resistor-

  • Remove the glove compartment to access the blower motor resistor.
  • Disconnect the wiring harness and unscrew the blower motor resistor. It might be easier sometimes to remove the blower motor resistor first, depending on the location.
  • The resistor will slide out of the HVAC housing after you harness the wiring and unscrewing. Before completely replacing the resistor, connect it loosely and check if all the fans are working. If everything looks to be working just fine, fully install the new blower motor resistor.
  • Tighten the screws of the resistor and reattach the wiring harness.
  • Reinstall the glove compartment.

Once the procedure is complete, you have successfully fixed the blower motor issue! All your AC fans should be working properly from now on. You will also be able to change the fan speeds accordingly.


Question: Does a Chevy Silverado 98 have a cabin filter?

Answer: The Chevy Silverado 1998 does not have a cabin air filter. This air filter is also known as AC filter or pollen. Instead, it has a plastic mesh that prevents foreign objects from entering the HVAC system. It’s an essential component for people with allergies and respiratory problems to create a comfortable environment.

Question: What is a Mode Door Actuator?

Answer:  Mode Door Actuator dictates the trajectory of the airflow through vents. This actuator door has two states. Open and Closed. Mode Door Actuators are controlled electronically these days. It differs from the blend door actuator, which helps to control the air-passing to control temperature.

Question: What happens if you put the cabin air filter upside down?

Answer: This will make it difficult for the air to flow past through the filter. As a result, the AC will have to work harder to compensate for the airflow loss. Doing this can damage your air conditioner in the long run.


You have completed the guide on fixing 1998 Chevy Silverado heater control problems. Now you can fix your HVAC within close proximity to your home. It’ll only cost you a few bucks to do so!

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