A/C blowing hot air

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h0op521
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A/C blowing hot air

Post by h0op521 »

The A/C in my 2002 Ford Explorer XLT is blowing hot air. When I turn on Max A/C, the A/C Compressor clutch engages albeit for a short cycle. The low pressure looks OK, but the high pressure does not.

Here's a video of the A/C Manifold reading: https://m.imgur.com/a/TBQQkiY

Can someone help me diagnose this? Is the high pressure line clogged? Does this mean I need to replace the orifice tube?

Thanks in advance for your help.
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JohnHere
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Re: A/C blowing hot air

Post by JohnHere »

Given the age of your vehicle, problems like this often result from a low-charge condition. I would begin by recovering whatever refrigerant is currently in the system, evacuate, and recharge with the proper amount of R-134a: Without rear A/C - 34.0 ounces; With rear A/C - 56.0 ounces. At the same time, adding a small amount of yellow fluorescent dye will help in leak-checking the system later if necessary.
h0op521
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Re: A/C blowing hot air

Post by h0op521 »

JohnHere wrote: Thu Apr 01, 2021 10:08 am Given the age of your vehicle, problems like this often result from a low-charge condition. I would begin by recovering whatever refrigerant is currently in the system, evacuate, and recharge with the proper amount of R-134a: Without rear A/C - 34.0 ounces; With rear A/C - 56.0 ounces. At the same time, adding a small amount of yellow fluorescent dye will help in leak-checking the system later if necessary.
Hi JohnHere, Thanks for your reply.

I found a local shop that evacuated my system, then I went to AutoZone and replaced the orifice tube (the old tube had a little bit of debris, but not too bad), and then went back to the shop to fully charge the system. The system took a LONG TIME to charge (at least 30 minutes), and periodically stopped and read "pressure building" before continuing to charge. The shop owner mentioned this was not a good sign. Even after we fully charged the system and turned on the A/C, hot air was blowing in the cabin. Looking at the pressure gauge, pretty much the same thing was happening as you see in the video I posted, only this time the high pressure gauge would flutter at a higher pressure now that the system was fully charged.

The shop owner mentioned that some of the A/C lines were running cold. I was in a rush to get out of the shop because I had limited time, and I wish I would have spent more time asking questions and diagnosing the issue. The shop owner thinks there is a clog in the high pressure line or possibly even a "collapsed hose" somewhere in the system. He recommended that I try to clear out the high pressure line and then bring it back to the shop to try again.

The shop owner mentioned I can use my air compressor to try to clear the high pressure line, or even use brakleen since it will evaporate. I still need to do a little more research to figure out how I'm going to try to clear out the system.

I'm also wondering if the high pressure is dropping somewhere along the line before reaching the orifice tube - Maybe, the Condenser or receiver drier / accumulator is bad. I need to get under the hood for a better visual inspection.

One more thing to add... There's another issue I'm facing where the air flow in the front of the cabin is very weak, but the air flow in the rear is normal. After doing some research, I believe the door that is located behind the passenger-side dash is broken and preventing strong air flow in the front of the cabin. This appears to be a common issue in Explorers. But I think these are two separate issues: 1) poor air flow due to broken door, and 2) a/c blowing hot air, even when the A/C clutch compressor engages. I don't think these issues are related.

I think my next steps are to try to clear out the high pressure line and repair the door behind the passenger dash. Really, I think the best thing to do would be to fully charge the system again, following the high pressure line with a digital thermometer and see where the temperature is dropping, and try to identify where the clog is. I will need to go back to the shop to do that, so I'm going to see if I can further diagnose the problem before I head back to the shop.
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Cusser
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Re: A/C blowing hot air

Post by Cusser »

1. There are aerosol cans of AC flush available at parts stores, then use your compressor to blow off any remaining solvents. I think one of the sponsors of this site sells kits fro professional mechanics.

2. I don't know specifically about your vehicle, but bad actuators could cause air to get deflected to the windshield or under the dash, or to the heater core. I would explore this. I believe our 2005 Yukon has 3 such electric actuators, and I replaced one on a friend's 2010 Ford truck.
Dougflas
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Re: A/C blowing hot air

Post by Dougflas »

Take it one step at a time. You do not need the refrigeration system to check and repair the inside blower system. Make sure the blower system is working correctly. 2002 model years probably used vacuum actuators to move the airflow if I remember correctly. There are repair kits in the field so you do not have to remove the dash to repair.
chrstopher007
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Re: A/C blowing hot air

Post by chrstopher007 »

The thermostat may have been accidentally set to “heat.” If this is the case, it’s easy to fix on your own. Flip the thermostat setting back to “cool” and see if the air conditioner begins to blow cool air again. Additionally, you want to make sure that the batteries are working and that the temperature is not set too high. Remember, the “auto” function only utilizes the fan when air is being heated or cooled. The “on” function means the fan will run 24/7 to circulate the air, even if the AC or heater is off. We recommend using the “auto” function most of the time and only switching to “on” when needed.
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JohnHere
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Re: A/C blowing hot air

Post by JohnHere »

From what I can see in your video, the LP side fluctuates between 15 and 30 PSI while the compressor runs momentarily...about normal. However, the HP side builds only to about 100 PSI, which is low, and points more toward a failing compressor, I think. With an ambient temperature around 80 degrees and a properly functioning compressor, the HP side should be about double that reading.

You could also have a clogged or partially clogged HP line caused by a collapsed hose lining. But in such a case--and presuming the compressor is good--the HP side would most likely be higher than normal.

As for the blower being weak in front, it's also possible that the evaporator case has accumulated a fair amount of leaves, dirt, and other debris over the years drawn in from the cowl, partially blocking airflow.
chrstopher007
Posts: 5
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Re: A/C blowing hot air

Post by chrstopher007 »

The thermostat may have been accidentally set to “heat.” If this is the case, it’s easy to fix on your own. Flip the thermostat setting back to “cool” and see if the air conditioner begins to blow cool air again. Additionally, you want to make sure that the batteries are working and that the temperature is not set too high. Remember, the “auto” function only utilizes the fan when air is being heated or cooled. The “on” function means the fan will run 24/7 to circulate the air, even if the AC or heater is off. We recommend using the “auto” function most of the time and only switching to “on” when needed.
tbirdtbird
Posts: 110
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Re: A/C blowing hot air

Post by tbirdtbird »

Christopher, I seriously doubt that you are a mobile AC technician.
This paragraph, which you repeated twice, actually applies perfectly to domestic equipment, and NOT AT ALL to mobile.

"The thermostat may have been accidentally set to “heat.” If this is the case, it’s easy to fix on your own. Flip the thermostat setting back to “cool” and see if the air conditioner begins to blow cool air again. Additionally, you want to make sure that the batteries are working and that the temperature is not set too high. Remember, the “auto” function only utilizes the fan when air is being heated or cooled. The “on” function means the fan will run 24/7 to circulate the air, even if the AC or heater is off. We recommend using the “auto” function most of the time and only switching to “on” when needed."

I am both a domestic and mobile technician, so I will be looking closely at your replies. We are supposed to be helping people here, not confusing them
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Tim
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Re: A/C blowing hot air

Post by Tim »

Sounds like he is referring to commercial a/c. Since he has not spammed the forum. I'll keep him active assuming it was an honest mistake. Will keep an eye out though.

As far as this vehicle. Seems to be short cycling. Evacuate, recharge, and see what the readings look like.
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