Jeep Wrangler HVAC Systems Through the Years

Climate control in the Jeep Wrangler’s cabin separates the joys of off-roading from the factors that will make any adventure miserable. During the winter season the heat will keep the cabin comfortable for those who dare to travel into the wild with their Wrangler and don’t want their toes to freeze off.

In the summer or hotter regions A/C keeps the cabin cool while the sun beats down on the mud and sand around them. Without either, you would only really want to drive your Jeep during the perfect in-between seasons.

Heating and air conditioning work almost the same across all platforms of Wranglers. This is because they are simple mechanisms that pump the desired air temperature through the ventilation system. Even for those who’ve never worked with HVAC will find the layout is rather basic and very easy to understand.

Heater Core: The heated air that is pumped into the cabin when the heat is turned on is actually gathered from the engine’s cooling system. The heater core looks a lot like the radiator in the Wranglers engine bay but in a much smaller package. As heated up fluid from the cooling system runs through the core, hot air is produced around it and that air is sucked up by the blower motor to heat up the cabin.

A/C Condenser: The A/C compressor can be found on the front of the engine of the Wrangler being spun by the pulley system. As the compressor condenses the refrigerant in the system it sends the compressed refrigerant to the condenser.

The condensed refrigerant has an extremely low boiling point and allows the condenser to work in the exact opposite manner since the condenser pulls heat out of the air around it to boil the refrigerant, leaving only cool air around it. This cool air is then cycled through the ventilation system.

Blower Motor: The blower motors role in the climate control system is to provide motion to the air to cycle it through the ventilation system. The speeds are controlled by the switch on the dashboard, and the dampers in the ventilation system dictate where the air is pushed to. When the switch is set to speed the motor engages and spins a fan that cycles the air.

YJ (1986-1995): YJ Wranglers had A/C as an option. These were barebones Jeeps that weren’t always equipped with the luxury of air conditioning. Kits are available to retrofit A/C systems to the YJ. Luckily heating was a factory option for all YJs so they weren’t all that bad. At the end of the YJs lifespan, R134a refrigerant would be required to be used for the A/C system instead of R12.

TJ (1997-2006): Designers of the TJ Wranglers thought of the drivers and equipped these vehicles with A/C for everyone. The drawback to these systems is that only the driver and passenger in the front seats were set up with vents. No ventilation runs to the rear of the cabin leaving rearward passengers to suffer. Every TJ Wrangler would be required to use R134a as opposed to the YJ which would have models to use either.

JK (2007-2017) & JL (2018 – present): The JK and JL heating and A/C systems are very similar to the TJ. Heat and A/C are available on all models and only the front of the cabin would have vents. Of course, updated components would be fitted to these models but it’s still a barebones design on either platform.

When the system goes down, heating and cooling being absent can provide a miserable atmosphere in the cabin of the car. There are a lot of parts in an HVAC system and this makes for a number of areas where problems may arise. When you look at common issues in the system, you can pinpoint the problem you are having and can quickly work to correct it. 

Heater Core: The heater core in a vehicle usually won’t go bad. If the heating is deteriorating this usually means a leak or other issue is present in the cooling system. Though a quick visual inspection of the heater core will tell you whether or not it will need to be replaced due to leaks or other damaged areas.

Blower Motor: A blower motor can burn up and when it does no air can be cycled through the system. If no air is being blown through the vents when the heat is turned on you will want to check fuses and wiring for the system before opting to replace the unit. 

Dampers: The dampers in a ventilation system are used to direct air to particular areas of the vehicle. If air is blowing through the system but not being directed appropriately it’s a sign the dampers will need to be replaced. 

Recharging A/C: A/C systems need to hold a proper charge in order to cool the air. If the A/C is starting to produce less and less cold air, the typical problem is the system will need to be recharged.  

Converting from R12: R12 is a harmful and potentially dangerous component that is obsolete. Many will want to update their system to run R134a as it is an environmentally friendly alternative and is a non-flammable substance. The only issue with R134a is that it doesn’t work to cool air as well as R12 does. One can run R134a through a system designed to use R12 but the A/C will not be as cold. To run R134 with the same level of cool air produced by R12, an updated compressor will need to be installed.