air flow issue
Thread Starter
5 Year Member
Joined: Apr 2013
Posts: 15
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air flow issue
Hi folks...2002 scab with a air flow heater/ac issue.On starting out for a drive there is strong air flow from vents or any other combination selected,fan speeds work in all selections.However after about half hour drive,fan speed(noise) still the same but air flow out vent almost done existant in either ac mode or heater.Heater and ac work fine only the air flow reduced to trickle.Shut the truck off for a few minutes and problem corrects itself.suggestions?checked for vacumn leaks but can't find any.thanks.
Junior Member
Joined: Jul 2018
Posts: 16
Likes: 6
At first glance this sounds like an a/c evaporator coil freezing over on you. Which is often caused by being low on refrigerant (due to the low evaporation temperature of refrigerant at a lower pressure...but not so low that it can't still get that cold).
Or does this happen after 30mins without the a/c on as well??
You may be able to pop the hood and see ice forming on your a/c components on the passenger side firewall when it happens. Or if you have a vent thermometer (check it in ice water first to make sure it's accurate) you can see if you have icy cold air in the 30-35 degree range--pretty decent indicator that the coil may be getting below freezing temperature.
Or does this happen after 30mins without the a/c on as well??
You may be able to pop the hood and see ice forming on your a/c components on the passenger side firewall when it happens. Or if you have a vent thermometer (check it in ice water first to make sure it's accurate) you can see if you have icy cold air in the 30-35 degree range--pretty decent indicator that the coil may be getting below freezing temperature.
Thread Starter
5 Year Member
Joined: Apr 2013
Posts: 15
Likes: 0
bang on
At first glance this sounds like an a/c evaporator coil freezing over on you. Which is often caused by being low on refrigerant (due to the low evaporation temperature of refrigerant at a lower pressure...but not so low that it can't still get that cold).
Or does this happen after 30mins without the a/c on as well??
You may be able to pop the hood and see ice forming on your a/c components on the passenger side firewall when it happens. Or if you have a vent thermometer (check it in ice water first to make sure it's accurate) you can see if you have icy cold air in the 30-35 degree range--pretty decent indicator that the coil may be getting below freezing temperature.
Or does this happen after 30mins without the a/c on as well??
You may be able to pop the hood and see ice forming on your a/c components on the passenger side firewall when it happens. Or if you have a vent thermometer (check it in ice water first to make sure it's accurate) you can see if you have icy cold air in the 30-35 degree range--pretty decent indicator that the coil may be getting below freezing temperature.