How To Fix RV Air Conditioner Not Blowing Cold

My fix for my RV/Toy Hauler air conditioner not blowing cold air.  My toy hauler is a 2008 Fleetwood Nitrous 23 foot with a single 13,500 btu air conditioner.  I’ve had it for 4 years now and I noticed lately that my RV air conditioner not blowing cold air, but more cool air.  It seemed to work to keep my toy hauler from not getting hot, but it wasn’t like a car air conditioner that cools everything off.

I spent the last couple of weeks trying to figure out what it could be. I was just about to throw in the towel and buy a new AC unit when I saw that they can cost almost $700.  At that price, I was going to investigate every last possibility before replacing it.

Ducted Air Conditioners

RV air conditioners come in 2 types, ducted and unducted.  Ducted AC works like central air in a house, it pushed cold air through ducts in the ceiling to send cool air to different parts of the room.   My toy hauler is a ducted type and found that this was the cause of my problem.  I was able to fix it with some foil tape and weather seal.  If you don’t have a ducted AC, the steps below can still help you troubleshoot an RV air conditioner not blowing cold.

Air Conditioner Type

My first thought for my RV air conditioner not blowing cold was that it needed to be charged.  There are 2 types of refrigerants used on air conditioners, R-22 which is known as Freon, and R143a. R-22 is being phased out and is really expensive to replace.  If you do have an R-22 air conditioner, it is set up from the factory as a sealed unit and doesn’t have any charging ports.  Basically a throwaway unit 🙁  If we can’t charge the AC unit, we need to look at other reasons for the RV air conditioner not blowing cold.

Clean Condenser and Seal External Seams

One reason for an RV air conditioner not blowing cold is clogged condenser fins and external leaks.  Dirt, leaves, and spiderwebs can collect in the condenser coils, so first make sure the fins are clean.  Also, you can use the foil tape to seal the blower box from the outside.

Clear Inside Filter

With an RV air conditioner not blowing cold, every little bit contributes to the AC cooling.  On the inside of the intake grate, there is a foam filter that can get filled.  You can clean it with soap and water or if yours is a couple of years old, just buy a new one. 

Clean the Evaporator Fins and Blower Motor

Next step is to clean the evaporator and blower motor fins.  We need to get all the dust and grime out of the grate so that air can flow freely.

Check Cooling Capacity

Now that we know the air conditioner is getting good airflow, we can check for sure if the AC unit is working.  An RV air conditioner will produce about a 20-degree difference between the intake and exhaust air.  The easiest way to check this is if you have a meat thermometer.  Check the ambient temperature of your RV.  Then start up your RV air conditioner and let it run for about 15 minutes.  Measure the air coming out of the exhaust vent of the air conditioner.  If the difference between the ambient temperature and the exhaust AC temperature is at least 20 degrees Fahrenheit it means the AC unit is working!  This is a good sign that the reason the RV air conditioner not blowing cold is not caused by low refrigerant levels but can be caused elsewhere.

Intake and Exhaust Leaks

The next culprit is the AC intake and exhaust having leaks.  There are 3 places where this can happen.  1.  Hot air leaking into the intake of the AC.  2.  Cool air leaking out of the exhaust before getting into your RV.  3.  Intake and exhaust air mixing.

Intake leaks

On each side of my AC intake, there are wires poking through the duct.  This might not look like a big deal, but the air being sucked in through these holes comes straight from the roof space of the RV.  It’s like a blowing a small stream from a hair dryer into the intake of your air conditioner.

Use the foil tape to cover up these holes.  I had wire hole openings on each side of my AC intake.

Exhaust Leaks

My toy hauler has a ducted AC feature where if you shut the main vents to the AC grill, it forces cool air to run through vents in the ceiling to cool my toy hauler down.  When I took the main grate off, it was clear that this was a major cause of my RV air conditioner not blowing cold.  The factory foil tape that was used to seal the ducts had practically fallen off causing huge gaps between the duct and the roof.  In essence, the cool air was blowing around the duct and straight into the hot roof cavity.

I peeled the factory foil off and used the weather seal foam to fill in the gaps.  I then went to town covering duct opening with the foil tape.

Splitter Leaks

Between the intake and exhaust of the air conditioner is a small foam insert.  The splitter has a foam ring that is supposed to seal the two sides from mixing air.  After years of vibration and breaking down, the foam causes leaks between the intake and exhaust of the air conditioner.  These leaks cause the cold air that the AC is making to be sucked right back into the intake.  The air conditioner is working, but the air is just circulating around between the intake and exhaust and never makes it into the RV.  To check for splitter leaks, put a flashlight behind the edges and look for light seeping through.

Just like with the exhaust leaks, use the weather seal foam and foil tape to seal up any openings.  I found there was a small gap between the roof and the base of the AC unit that I used some weather seal on.  The rest I just used many layers of the foil tape.

 

Result

After sealing all the leaks up, I could definitely tell that there was more pressure of air being pushed through the ducts.  My toy hauler got cooler faster and held a cooler temperature.  For less the $20 I was able to save myself from a new $700 AC unit.