A/C mod for cooler air

I might have to try this! Never been completely impressed with the AC on my 2013, i actually took it to the dealer for them to check the pressures and everything checked out fine.

It looks like you insulated the red line correct? Isnt that the "hot" side of the compressor? (AC systems have always kinda baffled me tbh)

 

I had this on my Matrix for 8 years and never had any issues with it. Worked great.

 

Start it up and turn on the AC. You will soon know which side is hot and which is cool.

 

interesting

 

I hate to tell you but this won't help a thing. There are two lines in the A/C system, the high-pressure line, which is the line that actually does the cooling by spraying high-pressure liquid freon (or R134) into the evaporator core, and the low-pressure side which is the return to the compressor. That line that feels cold or frosty won't be helped at all with foam. The only reason you see it covered in foam in a home A/C system is to keep air away from the cold line so condensation won't form and drip where you don't want it. Under the hood, condensation won't be a worry.

The cycle goes refrigerant sucked into compressor, pressurized high enough so that it will condense to a liquid when it goes through the condensor core in front of the radiator. Then that high pressure (and HOT) line goes to the evaporator core where the liquid refrigerant is spray in, and flashes to a gas, absorbing a LOT of heat, cooling the air that passes over the evap core significantly. This low pressure line (very cold) now makes its way back to the compressor and the cycle repeats. If you put foam around that line, you might gain a 0.5% efficiency since the gaseous refrigerant won't absorb extra heat on the way to the compressor, which then has to be extracted by the condenser core. But that is so tiny...

Best way to get the coldest air is to evacuate the system and add exactly the amount of refrigerant suggested by the manufacturer. This is one place where "more is NOT better", which is a common mistake. Too much refrigerant results in too much pressure on the low pressure side, making it harder to boil off the refrigerant in the evaporator core. You can look up a chart online to see the temperature r134a boils at depending on the low pressure. As the low pressure side goes up, so does the boiling point, and that increases the temperature of the A/C discharge air since the R134 can't extract as much heat at high pressures. You CAN add so much you hydro-lock the compressor and blow it out, if you go crazy. If you under-charge, you can suffer from freezing in the evap core, where the condensate from the air freezes and blocks the evap core, and air temp rises.

There really is a "just right" (or goldilocks) zone. Those silly recharge kits sold at auto zone have done far more damage than good. And not all A/C systems run at the same pressures. I have a manual I use that lists high/low side pressures for each specific vehicle year and model. There are lots of variables, and thinking that a "one-size-fits-all" freon recharge kit will do what is needed is as likely to hurt as help. Do it right and it will perform as expected.

There are lots of things that will cause warmer than desired outlet air. Moisture that freezes and blocks the orifice tube or tx valve, compressor seals / valves that wear and have a lower than required high (outlet) pressure and/or a higher than required low (inlet) pressure. Crap in the evap core. Low refrigerant charge. A good set of A/C gauges helps spot almost anything that can go wrong, if used correctly.

 

Just an idea, but usually if the a/c gets warm when idling, the fan clutch could be bad. If it's not fully engaging and pulling enough air past the condenser, it will cause the a/c to get warmer since it's building higher pressure. When driving you won't notice it since plenty of air is running through the condenser.

I haven't done it yet to my '15 but in most of the vehicles I've had in the past that used a fan clutch, I installed a pusher fan that cycles on with the compressor and makes for a nice cold a/c and keeps pressures in check when idling for long periods and has the added benefit of air flowing across the radiator as well. Of course this is in AZ where summers are HOT!

 

I had wanted to but I grow impatient and just do stuff.

 

I insulated the read one (the cold, larger of the two).

 

I appreciate your input but there is absolutely a difference. I've had the truck for 2 years with lackluster a/c performance, even had it checked at dealer, and checked myself. Now it actually gets cold like other new vehicles, not just cool.

 

The Yota dealer (supposedly) checked it and I put the gauge on it. Seems within the operating range.

 

which way does the coolant flow in this system? In my picture above does it flow through the red line into the compressor and out the green line. Or visa versa?

If i had to bet its in through the red line (hot side) and insulating that line makes it to where extra heat is not added to the system before its compressed?

 

Correct. Output of the compressor goes into the condensor and this line (green in your diagram) is hot compared to ambient.

In theory yes, the return from the evaporator to the compressor (red in your diagram) will be cold compared to ambient. Thus insulating it would in theory reduce the amount of heat from the ambient entering the system. How significant that would be I have no idea.

Hopefully I got that right, A/C systems are in no way something I'm very familiar with beyond the very basics!

 

This is called the placebo effect. You changed something. You wanted it to work. You believed it worked.

The test is a digital thermometer in the air duct. That "cold" line has already done its work by the time it is cold, insulating it won't do a thing.

Now let's see if we can figure out why this _might_ work.

Suppose you live in Death Valley, and you go for a drive where the ambient air temp is 135 degrees. And your compressor is a little worn, or you are a little low on freon, so the highest pressure the compressor can produce is about 200 psi. You will find that the A/C will barely work. Because at 135 degrees, R134a won't condense at 200 psi very well, if at all. You are right on the "ragged edge". If you can protect that low side by insulation, you pick up less heat, which will give you a chance of condensing some liquid refrigerant as it passes through the condenser, and you will get some cool air. But that is "on the ragged edge". R134 will condense at lower pressures at more normal air temps, and any extra heat you pick up on the return line goes out through the evaporator anyway. So rather than a few degrees cooler, you might save 0.01mpg or something since the engine is driving the compressor. I rode through Death Valley back in the 50's in an air-conditioned Chrysler. It did NOT work. It was pretty mediocre in the hot south anyway. But compressors have come a long way, even though we took a step back with the move to R134a.

Insulating the liquid/high-pressure line is probably going to harm things. I'd bet at highway speeds the air under the hood is cooler than the temp of that high pressure line, which means it would be radiating heat before it hits the evap core, allowing the refrigerant to absorb more heat from inside the truck.

When low pressure gets into the 20's, that's borderline also, because the R134 will boil and drop the temp to a little below freezing, NOT what you want in the evap core since it will freeze up and the ice will block airflow. Good gauges list the various pressure/boiling point (low side) or pressure/condensing point (high side) to give you an idea of where you are at.

 

In theory it makes sense. That line that is getting insulated is the "low pressure, cold side". So if we insulate it and dont allow extra heat to enter the system before the compressor, the compressed refrigerant is at a lower temperature to begin with before having extra heat removed in the condenser.

Could probably also benefit from insulating the hot side that goes to the evaporator.

 

It doesn't make much sense to me, having worked on these things for years. The freon in the low side is a gas. It is "hauling a$$" through that tubing because the compressor is sucking like a biker's old lady. (once saw someone tell a joke about having a girlfriend that could "suck-start" a Harley. ) It is not going to pick up much heat and once it hits the compressor the temp is going to shoot WAY up anyway after compressing. The path thru the condenser is pretty long and I doubt you could measure 1 degree difference insulated vs not where the liquid comes out of the condenser. That is not going to translate to much of a difference at the evap core. A fraction of a degree, maybe.

The high side insulation will almost certainly hurt, because that tubing is HOT under load, and it will radiate more of that heat between the condenser and the evap core. Again, if you sit at idle in death valley it might actually help. MAYBE. But driving down the road I would bet it would hurt. A simple test would be an ohmmeter with a temp probe. Stick the probe in the vicinity of (but not touching) the liquid (high pressure) line. Then stick the probe directly on the liquid line. Compare the temps. If the liquid line is higher, insulation will hurt. If it is lower, insulation will help some. If they are close, it's a break-even waste of money. That would be the way to answer this accurately.

 

Insulating the liquid side will have no effect either.

 

Robert hyatt knows what he is talking about..............listen to his advise.....

 

Looking for ways to mod your A/C? You can add a switchable fan to the condenser for traffic/slow trail riding conditions. One that works great is a Honda CBR radiator fan.

 

All of the cooling takes place at the expansion valve what comes out the other side is hot.

 

Really? So what happens to a gas when it's compressed?