Automotive Air Conditioning Information Forum

For the first time, I hooked up a set of gauges to my vehicle and would like to review the results with this group here.

Be patient, I am still learning, but always enjoy a good challenge and value the "eye of experience" from others.

The Car: 2013 Honda CRV with 118k miles.
Condition: AC not cold enough...sometimes it surprises me with colder operation, but for the most part it struggles to cool at very high ambient temps.
Cause: ?? (low on freon it seems... based on the data below).
Correction: Hopefully just recharge it.

So, I have compiled a google drive consisting of walk around videos plus photos. One observation, is that I believe the valve core on the low side, might be leaking, since after pulling the gauge set off, I noticed a touch of oil (?) on the inside of the VC....basically on the face of the brass.

Initial Walk Around Video:
https://drive.google.com/file/d/1xEIatA ... sp=sharing

The Valve Cores:
https://drive.google.com/file/d/1_bOuoB ... drive_link

Full Folder:
https://drive.google.com/drive/folders/ ... sp=sharing

Looking at the PT Chart (attached) I found online, it seems I am just low on refrigerant. It was around 94* degrees ambient at the time.

Thanks in advance for any and all help!

What type of a/c tools do you have? You have inquired about multiple projects, which is perfectly fine . You need the right tools for the job.

The only way to know if it is low on refrigerant is to reclaim what's in the vehicle and measure it. That is the process you should start with every time you start working on a vehicle. Get the OE baseline for the vehicle set so you know what it should be doing. Take all guesswork and 20 questions out of the picture.

I've learned this from the best: Check your tools. For some reason, your pressures don't match what you're measuring at the vents, at least in my experience. Hook up your gauges to another (known good?) vehicle and make sure the gauges, hoses, and connectors are all in good shape.

That being said, if the tools are good, I'm surprised that the compressor is still running with that low of a low side. Usually the pressure sensor will cut off there somewhere. What's the reading, 25psi at idle? What are your readings at 1500 rpm? I use a stick or something and then adjust the power seat controls to fine tune how much it presses the gas pedal, lol.

It certainly seems that you are quite low on refrigerant. I'd charge up about 6oz in there and see what happens.

Also, you can spray soapy water on the Schrader valves to check if there's a leak.

The Tools I have so far, are borrowed gauges and vacuum pump (used once) and the Mastercool valve core removal kit.

I understand the notion and preference of charging by weight vs. psi alone. I will have to take a reading at 1500 rpm. Does the little droplets of oil on the face of the valve core perhaps indicate a leaky valve core? I'll spray some soapy water on it and see.

I was hoping to charge it, even if a little under, to get it operating again and if it leaks out in due time, then I know it's time for it to see the mechanic. How bad of an idea is this? If so, I am not opposed to taking it in and getting it done right.

The only other observation I can add....when driving with the temp probe in the vent...on a 95* degree day, I am getting near 70* out of the vents in city driving, but when on the highway, the number drops to 60*. I know that more air is passing over the condenser at speed, but should it make this much of a difference in temperature readings? What could it possibly point to? Additionally, this morning it was 74* and after arriving at my location, with the fan speed on a low setting, the temperature out of the vent was in the mid 40's. If it's this low on refrigerant, should it be able to get that low, even though the solar load isn't anywhere near its peak yet?

fastsvo wrote: ↑Thu Jun 27, 2024 12:10 pm Does the little droplets of oil on the face of the valve core perhaps indicate a leaky valve core? I'll spray some soapy water on it and see.

Don't know, maybe it came from another fluid, or when you had gauges on it? The high pressure side makes a little 'burst' when you remove the coupler from the valve. Soapy wooder will reveal if they are actively leaking. I usually spray some compressed air after so the water doesn't linger on the ports.

fastsvo wrote: ↑Thu Jun 27, 2024 12:10 pm How bad of an idea is this? If so, I am not opposed to taking it in and getting it done right.

Not a bad idea. Nothing wrong with charging it up a little so see if your pressures change or your cooling gets better. I think almost all a/c cooling issue diagnosis are started with a top up (if pressures are low) or a full, recovery, evacuation, and recharge if no other obvious signs of problems.

fastsvo wrote: ↑Thu Jun 27, 2024 12:10 pm The only other observation I can add....when driving with the temp probe in the vent...on a 95* degree day, I am getting near 70* out of the vents in city driving, but when on the highway, the number drops to 60*. I know that more air is passing over the condenser at speed, but should it make this much of a difference in temperature readings? What could it possibly point to? Additionally, this morning it was 74* and after arriving at my location, with the fan speed on a low setting, the temperature out of the vent was in the mid 40's. If it's this low on refrigerant, should it be able to get that low, even though the solar load isn't anywhere near its peak yet?

Yes, it will get that low even if low on refrigerant because there's just not much heat load. Heat load is everything for a/c performance. Also lower fan settings will give you colder temps at vents.

My non-professional advice is try a 6 oz top up and monitor closely if your pressures get better or stay the same given the conditions. Check at 1500 rpm or more.

Your car has an 11-year-old scroll compressor with a heat switch (thermal switch). That type of compressor isn't renowned for its longevity, and the heat switch itself is also prone to failure.

From your videos, I have a hard time seeing the pressures, especially because the Manifold Gauge Set you're using is an international-style MGS showing "bar," I think, as the primary scales. I can make out the LS pressure, which at 30 PSI (second scale in) looks good. But I think I see that the HS pressure is low.

If you're planning to keep the car a while, I would do as Tim suggests and first recover the charge (or have it done), remove the compressor, and pour out the oil. It should be light amber in color. If the oil looks very dark or black, possibly with metallic particles in it, you'll definitely need to replace the compressor, along with the condenser, which comes with an integral Receiver/Dryer, and flush-out the rest of the components with solvent.

I wouldn't worry too much about the Schrader valves leaking. Most of them do to some extent. The plastic caps in good condition will provide the final seal. But as long as you have the system open, that's a good opportunity to replace the Schrader valves, as well as the caps, if you so desire.

P/T charts can often be misleading. Looking at the chart you posted, at 90°F, it says that the low side should be between 45 and 55 PSI while the high side should be between 250 to 270 PSI. At the median of 50 PSI on the low side, the evaporator will be around 50°F, hardly cold enough to provide much of any cabin cooling. And at the median of 260 PSI on the high side, the system wouldn't have effective condensing (changing the state of the refrigerant from a gas to a liquid). The result would be warm center-vent temperatures.

Lastly, "topping-up" the refrigerant is not considered a Best Practice because you don't know how much refrigerant a system contains, nor do you know how much you're putting in.

Per my eyes I'm reading 25, low and 165 high in his video, and that's right at startup when the vehicle is hot inside and 90f+ ambient. Those reading are definitely low.

easier this way


Low side: High side:

JohnHere wrote: ↑Thu Jun 27, 2024 2:21 pm Your car has an 11-year-old scroll compressor with a heat switch (thermal switch). That type of compressor isn't renowned for its longevity, and the heat switch itself is also prone to failure.

From your videos, I have a hard time seeing the pressures, especially because the Manifold Gauge Set you're using is an international-style MGS showing "bar," I think, as the primary scales. I can make out the LS pressure, which at 30 PSI (second scale in) looks good. But I think I see that the HS pressure is low.

If you're planning to keep the car a while, I would do as Tim suggests and first recover the charge (or have it done), remove the compressor, and pour out the oil. It should be light amber in color. If the oil looks very dark or black, possibly with metallic particles in it, you'll definitely need to replace the compressor, along with the condenser, which comes with an integral Receiver/Dryer, and flush-out the rest of the components with solvent.

Can the oil be removed during vacuuming?

Only a couple times, have I heard from what I thought was compressor knock upon start up on a cold night, when the A/C was already engaged when I had parked it earlier. I immediately turned it off from fan speed = 1, to 0 and then back to 1, in order to test it. I would hear some light knocking and then it went away.

An insignificant amount of oil is removed during vacuuming