Common Reasons Why An Outdoor HVAC Unit Won't Turn On

20 September 2018
 Categories: , Blog


In many areas of the country, the summer months bring sweltering heat, and running the air conditioner throughout the day and night is necessary. If you live in a very hot climate, it can be very alarming to turn on your home's air conditioner only to find warm air blowing through the vents. If this happens, it is important to go outside to see if your outdoor HVAC unit is running. If it is now running at all, it can be due to several issues. Here are some of the most common reasons that an outdoor HVAC unit won't run:

Burnt Wires

Your home's air conditioning system consists of both an outdoor HVAC unit and an indoor air handler. The outdoor unit needs to be operating properly in order for cold air to be produced and forced into your home. One common reason that an outdoor HVAC unit can cease to operate is due to burnt wiring within the unit. When wires are old and become burnt, they can't conduct the electricity needed to properly run the unit. Burnt wires inside an outdoor HVAC unit can be repaired, but the repairs should always be done by an experienced HVAC technician.

Bad Capacitor

A capacitor is a device that stores energy, similar to a battery. It is the shape of a cylinder, and the energy stored within is needed to get the fan started. Capacitors typically do not last as long as the HVAC unit itself, especially in very hot climates. One way to tell that a capacitor is bad is by examining the ends-- a faulty capacitor will have noticeable bulges. It is possible for a homeowner to purchase a capacitor and replace the faulty one, but it is highly recommended to have this job done by a professional.

Malfunctioning Time Delay Relay

A time delay relay is a component in the outdoor HVAC unit that receives a signal from the thermostat that indicates that the HVAC unit needs to produce cold air. When the time delay relay goes bad, the outdoor HVAC unit will never receive the signal that it needs to turn on. Thus, your air handler will begin blowing air into your home, but it will be warm air, not cold air created within the outdoor HVAC unit. An experienced air conditioning services will be able to diagnose a bad time delay relay switch and replace it with a brand-new one.