This article outlines the basic troubleshooting steps when you are experiencing a heating issue with your unit.

The heating season is just as important as the cooling season in maintaining your unit. When experiencing an issue with your heat, we ask you to follow these steps to determine the root cause. When testing the cooling, check the following;

Change the mode on your display or thermostat to heating and fan speed to auto. We will need to set the temperature above your room temperature to call for heat. Once set, listen to a clicking noise for the indoor fan and electric heat to turn on. This means the unit has received the communication from the mainboard. Usually, you will smell heat or a burnt smell when the electric rod is being heated up. This is what produces the heat and the fan blows the air through the vents. We recommend placing your hand on the vent for a couple of minutes to confirm how it feels.

Steps to take to determine the issue:

1. Check to make sure all the settings of your PTAC unit, including the fan and temperature settings, are set correctly.

2. Make sure the air filter is clean and free of debris.

3. Check the air vents to ensure they are not blocked and that air is flowing freely.

4. Make sure the outside unit is free of debris and that debris is not blocking the condenser coils.

5. Check the compressor and other electrical components for any signs of damage or corrosion.

6. Inspect all the ductwork for any signs of damage, blockages, or leaks.

7. Is both parts of your universal power cord plugged into the unit? (GCDM only)

Issue: No Heat

We would need to confirm the below before troubleshooting;

• Is the unit working operating from the thermostat or display? If the thermostat, click HEAT and + to change the unit back to operating on the display. 
  • Turn on the unit and call for heat using the display to see the behaviour. If the same behaviour when operating the thermostat, move on to the below steps. If not, the issue is within the thermostat
• Is there anything placed in front or around the unit causing debris to build within the unit or blocking the air from flowing freely? Below is an example of a clean
  • Visit more information with Recommended PTAC Installation Clearance – Genuine Comfort
  • OR Common Mistakes – Genuine Comfort
• How many clicks and what physically turns on when calling for heat? *Be sure to wait a minimum of 5 minutes to see if the heat is turning
  • Does the indoor fan turn on?
  • Do you feel and/or smell the electric heater running? When turned on, there is a moment of a burnt smell. Or can feel like the temperature is rising and becoming warm
• Using a temperature probe, what is the temperature before and after calling for heat? 

If the above questions do not show signs of the unit providing heat, follow the steps below.

1. Check your plug to see if there is power
2. Is your unit running off the display or thermostat? If the thermostat, change the unit back to display mode.
3. If the unit is continuing to experience the same issue, identify if your mainboard has any burnt marks. Burnt marks mean the fuse or there is a short circuit in your unit.
4. Continue to test your relays if there are no visible burnt marks.
5. Testing the high and low limit fuse.

Test your Relays

1. Keep the unit powered on, and adjust the multimeter to the ohm gear. The goal is to measure the resistance of the relay

2. Connect the red and black probes to the output terminal of the relay at random, and observe the resistance on the multimeter; Observe the resistance value on the multimeter compared with the nominal value (120 Ω± 10%). 

3. If the resistance value is normal, the relay is normal; If the resistance value is too small or 0, the relay coil is short-circuited partially or completely, and the relay is damaged, so it needs to be replaced.

Example:

You have a 3.6 electric heater not running (using 3.6KW & 5KW heaters as an example). 

• The normal resistance of the heater can be calculated as R=U*U/P, U is rated voltage, and P is rated power.
• For 3.6kW@230V, the R is 14.69 Ω.
• For 5kW@230V, the R is 10.58Ω.
• For 3.6kW@265V, the R is 19.5Ω.
• For 5kW@265V, the R is 14Ω.
• The resistance varying range should be within 15%

Solution: 

Check the red and blue wires connected to the relays, and see the circles noted in the image below to 3.6kW@230V is measured as 13.2Ω. The thermostat and thermal fuse are almost 0 Ω, if measured over 5 Ω that is broken.

Testing your Limits

Your electric heater has limit switches to ensure the heater is providing the needed heat to feel warm air pushing through the vents.