A/C hot on startup, then cold. Normal?

[lil_Blue_Ford]

I’ve developed a couple things that I tend to do to help combat the whole hot truck and takes awhile for the AC to catch up.

The window vent things so I can leave the windows cracked open and not worry about rain. This is a massive help on hot days and leaving the truck parked in the sun.

If I’m not in a hurry to go, open the windows and leave a door open for a couple minutes to help vent. Even better is to start the truck and turn the fan on high for a minute before engaging the AC and give it a minute to get all the hot air out of the vents before getting in.

Tint helps cut down on solar heating in the cab.

 

[Angry Possum]

I’ve developed a couple things that I tend to do to help combat the whole hot truck and takes awhile for the AC to catch up.

The window vent things so I can leave the windows cracked open and not worry about rain. This is a massive help on hot days and leaving the truck parked in the sun.

If I’m not in a hurry to go, open the windows and leave a door open for a couple minutes to help vent. Even better is to start the truck and turn the fan on high for a minute before engaging the AC and give it a minute to get all the hot air out of the vents before getting in.

Tint helps cut down on solar heating in the cab.

Yep, I always leave my windows cracked in the summer on my 93 Ranger. I have the window rain guards, I'm not too worried. Also that windshield solar thing works great too. Parking in a shaded area is also a big plus.

 

[Angry Possum]

FWIW, my son and daughter have those AC issues when it's hot out and they are in idle or stopped at a light etc, one has a Mazda, the other a Sonata.

I'm gonna look into if the radiator fans change speeds when the AC is turned on. In what I had read some cars that only have one radiator fan. However when u turn on the AC that one radiator fan now goes into a higher speed.

 

[lil_Blue_Ford]

FWIW, my son and daughter have those AC issues when it's hot out and they are in idle or stopped at a light etc, one has a Mazda, the other a Sonata.

I'm gonna look into if the radiator fans change speeds when the AC is turned on. In what I had read some cars that only have one radiator fan. However when u turn on the AC that one radiator fan now goes into a higher speed.

Some cars also have an electric pusher fan that kicks on to help cool the AC condenser

 

[fastpakr]

Now I’m trying to remember which manufacturer has (had?) an automatic solar powered system to open a small vent and run a fan to keep interior heat down when the car was parked. Seems like something Mercedes would do.

 

[Angry Possum]

Some cars also have an electric pusher fan that kicks on to help cool the AC condenser

Yes I know. Thanks

 

[cbxer55]

Yep, I always leave my windows cracked in the summer on my 93 Ranger. I have the window rain guards, I'm not too worried. Also that windshield solar thing works great too. Parking in a shaded area is also a big plus.

That's what I do. AC in my 98 hasn't worked for over 20 years. Don't miss it. I'm a windows down type of guy, no matter the weather. Even though the AC in my 04 Lightning works, I rarely use it. Couple times a year to keep things fresh. Otherwise, windows down.

 

[lil_Blue_Ford]

My F-150 will blow snowflakes out of the vents in AC mode. I rarely use it, mostly long drives or traffic or hot and humid with rain. Even a lot of long drives if it isn’t miserable out, the windows are down and the wing vents open. I’m a little irritated that my only rigs with wing vents are my F-series trucks and my 88. I’m intending on swapping to wing vent windows on the Choptop and if I fix it the 92. A little bummed that’s not an option for my 00 Rangers.

 

[Lefty]

My F-150 will blow snowflakes out of the vents in AC mode. I rarely use it, mostly long drives or traffic or hot and humid with rain. Even a lot of long drives if it isn’t miserable out, the windows are down and the wing vents open. I’m a little irritated that my only rigs with wing vents are my F-series trucks and my 88. I’m intending on swapping to wing vent windows on the Choptop and if I fix it the 92. A little bummed that’s not an option for my 00 Rangers.

I pulled one of those rear windows that open for my regular cab. It really improves the air flow inside. And it also does a pretty good job of keeping the cab from heating up when it's parked

 

[ekrampitzjr]

It is natural to have hot air at first. The sun has been heating up the cab. But the AC system hasn't been running. You start the truck and turn on the AC. That starts the cycle. The compressor gets moving and starts building pressure and moving refrigerant. The refrigerant isn't naturally cold. It has to move through the system and do the scientific magic. It takes time. Once the system is running, it can only do "so much". It has a capacity. Think of it as being able to change the air temperature by a certain number of degrees. Let's say 30 degrees (this is just an example). So, if the air in the cab is 110 degrees, and the system can drop it by 30, then it will initially put out 80 degree air. Of course, that 80 degree air is mixing with 110 degree air. So you don't feel much relief yet. As more air is changed to 80 degrees and mixes, eventually, the air in the cab is only 100 degrees. 100 degrees minus 30 degrees means the system starts putting out 70 degree air. Then that mixes with the 100 degree air. And so on and so forth. Eventually, the air in the cab is 80 degrees. But, remember, the sun is still trying to heat up the cab. It's a continuous fight. Eventually, you hit and equilibrium where the system can't get any cooler. This is because it has reached its maximum capacity. The sun is putting heat in as fast as the system can remove it because the system is trying to put that heat outside where the air is already hot. When you get gauges and check pressures, you have to use a chart that is based on the ambient outside temperature. We generally think of AC systems making cold air. But what the really do is move, or transfer heat. There has to be a place to put that heat. And when it's blistering hot outside, it is more difficult to move heat from inside to outside.

It's like a little guy digging a hole. Eventually, he gets to a point where the hole is too deep and he can't throw the dirt any higher to get it out of the hole and it keeps falling back in on him as fast as he shovels it out.

The moral of the story? Make sure your system has the right amount of refrigerant and make sure the condenser coil (out in front of your radiator) is clean and not full of bugs and mud. And make sure the evaporator coil (in the AC duct) is clean and not full of leaves, dust, McDonalds receipts, etc.

Exactly all of this. It's normal on really hot days, when my Ranger has baked in the sun, for hot air to come out of the vents for the first couple of minutes before feeling any cool air. My truck is the common dark-gray charcoal metallic color, not too far from black, which means the cab and air plenums in the dash get really warm in the sun. (I see why my dad preferred white vehicles.) Since it's a pickup, the cab is small compared with a regular car, so the interior gets hot quickly.

The A/C has to push all of the hot air out of the plenums and cool the plenum network before any cool air can get to the vents. That takes a little time.

Once I get cool air, the interior stays cool, so I know there's no fundamental problem in the system. Last year the Schrader valves were replaced and the system held full charge afterward.

Even when it's pushing 100° F outside, after feeling cool air, I can normally turn the switch back from max to regular A/C and the A/C will still maintain comfort.

By the way, parking in the shade when that's an option makes a big difference on hot, sunny days.