In the last week I have noticed my Air Conditioner not blowing as hard after it has be on for say 30 minutes. When I first turn it on it seems to work fine, but after 30 minutes it seems to lesson in blowing power. Its still spitting out cold air, but I have it on high and its blowing as if its on low. I checked the air filter and while it wasn’t perfect i don’t think that’s the issue. Some have told me it could be a relay issue? or possibly the blower motor. Someone also said try recharging it and see if that would help. Any advice or experience with this issue would h helpful!
If you have Automatic Climate Control in this vehicle, it will lessen the speed of the blower motor as the interior cools-down. Does this vehicle have Automatic Climate Control?
Also… can you adjust the blower speed upward with the manual controls when the blower speed lessens?
Mine doesn’t have automatic climate control.
I have the blower speed the max it will go. it just has 4 options 1,2,3 or 4. I run it on 4 and after 30 minutes or so it will lessen as though I turned it to 2.
Maybe the evaporator is freezing up. When the A/C is working normally look underneath the car about where the passenger’s feet would be and note if you see a condensation drip. That is normal.
When the A/C is not working as it should look in the same area and see if there is no condensation drip. That could be a sign of a frozen evaporator.
It’s normal for an auto A/C to lose a bit of refrigerant over the years and that can affect the system pressure. The A/C gauges need to be hooked up and take a look at the high and low side pressures; both at idle and at elevated RPMs. Say about 1800 RPM or so.
now that you mention it i haven’t seen a drip this year too much. That could be it. Whats the solution to prevent it from freezing up?
The airflow speed is not dependent on A/C charge level. Regardless of A/C settings, the fan should blow consistently over time. Setting 4, the max setting, bypasses the resistor block and uses a relay to power the fan. If the fan is slowing down, especially as it runs over time, I suspect the bearings are wearing out and the fan blower needs to be changed.
If this is a case of frozen evaporator then an small amount of added refrigerant could take care of that problem.
As I said, if there is no condensation drip the A/C gauges need to go on and find out what’s going on with the high/low pressures at idle and elevated RPMs. If the low side is lingering below freezing that could freeze the evaporator up.
A slight correction. By the low side pressure (and this is not etched in stone) the low side press. is roughly equivalent to the evaporator temperature so E.G. a 30 PSI reading would be roughly equivalent to 30 degrees. Ideally you want the low side around 35 or so.
If the evaporator is freezing up because of a low charge, air flow will be restricted.
So turn off AC but leave fan on. If it starts blowing at normal flow in a few minutes, it would verify evaporator icing up.
A shop could monitor the voltage at the fan’s power inputs before it slows down, then after. If the voltage isn’t changing before/after the problem must be the fan motor or the blower cage or something obstructing air flow. If the voltage is changing, then they’d work backwards toward the battery to find out why. A faulty relay or a high resistance harness electrical connection at the fan motor seems possible.