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Problem: Loose Insulation mats inside blower compartment are causing our AC to freeze up?

troubleshooting air condtioners and heat pumps

Problem: We experienced low air flow in our vents so we changed our air filters, then looked at the unit in the attic to find that our evaporative coils were frozen and (what I think are insulation mats) located above and below the blower are being sucked in by the blower. We ran the fan alone with the ac off to defrost the coils but the insulation mats were still blocking the air flow. My question is what is the purpose of these mats and will our unit be okay without them? If they must be replaced, will we be able to purchase and replace it ourselves? Thanks for your time & may God bless all your endeavors!

Answer: Thanks so much for your blessings, interest in our website and the opportunity to do business with you! Thanks for asking a great question! Yes, I have seen what you describe happen several times before. The mats which are glued to the metal body of the furnace or air handler come lose and restrict the air flow going into the blower! The insulation mats are used to reduce noise and prevent heat or cold (winter time) transfer, build up inside your air handler. Without the mats you might get noisier blower air flow and you might get some heat entering the return from the hot metal duct work in your attic. The insulation keeps the heat out so that you do not get hot air pulled into the return. If it was me I would try to purchase some spray glue at home depot to re-attach the insulation pieces. Sheet metal shops use a special duct work insulation glue to glue the insulation in place. If the glue does not hold I would remove the inside insulation and insulate the duct work on the outside. Here in Louisville, KY it is HVAC code to have ducts insulated in unconditioned spaces like attics and crawl spaces. The insulation keeps the duct work from heat or cooling lose or gain. The supply lines are insulated to keep them from sweating water in the summer time. I hope you can easily get this fixed. I know that nothing is easy when working in the attic. Hope you can work up there in the early morning before it gets real hot! I hope that you have a blessed day and week!

Steve Arnold, https://arnoldservice.com

6 thoughts on “Problem: Loose Insulation mats inside blower compartment are causing our AC to freeze up?

  1. We have had the same thing happen. It took 21/2 years for the HVAC company to figure out our problem. My question is this — Is there any chance of fire or other “disaster if those are not there? I know when I tell the company I want them replaced properly I am going to get “push back from them and have to fight to get them reinstalled properly.

    1. No sir, there is no chance of fire or other disaster if the insulation mats are not there. There main purpose is for noise reduction and if the furnace is installed in an attic space or crawl space to keep cold air or heat from infiltrating the blower chamber. If your furnace is in an unheated crawl space or attic then I would have the insulation replaced. Thanks so much for your post. Steve

  2. We were experiencing low air flow cause of the insulation mats being sucked in by the blower. i did not know it at first though, our problem was in the heating i thought it was my board cause of an error 5 so i replaced my 20 year old one than a day or two later it starts kickin out a code 4 and doing some research & i checked the insulation above the fan cause my furnace also is in the attic laying on its side and i should have noticed it before, but i took the insulation out and now the fan blowing good and strong and should not kick the high limit switch,but i ordered a new one anyhow, along with running a new thermostat wire and stat,the old stat was a mercury filled ha.Insulation board on the outside is a good idea thanks.

    1. Hi Casey! Thank you so very much for sharing how you fixed your furnace’s poor air flow problem. Believe me I have had similar situations where I have replaced expensive parts when in the end found out it was a simple problem. I know that your post will help others in finding an inexpensive fix to their furnace or air conditioner problems. God bless you. Thanks so much! Steve

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