Freshly repaired A/C system short cycling.

[Tim]

Best Practices suggest replacement of both the Receiver/Dryer and o-rings. The desiccant in the R/D captures and retains any moisture that's introduced into the system and can't be rejuvenated. You might be able to re-use the o-rings if they aren't deformed, nicked, or torn. Give them a thin coat of PAG oil or Nylog Blue before installation.

Ok, so I did exactly that. I replaced the expansion valve with the Denso, replaced o-rings where I disconnected the lines and replaced desiccant. I vacuumed and filled by weight. I still get about the same readings...

1500 RPM
200-210 High
20-25 Low
80f ambient temp

I at my wits ends now to be honest... Do you have any other ideas ?

Thanks !

20-25 low should get the coil pretty cold. I would check the blend door or hot water in the heater core.

[gabton]

Best Practices suggest replacement of both the Receiver/Dryer and o-rings. The desiccant in the R/D captures and retains any moisture that's introduced into the system and can't be rejuvenated. You might be able to re-use the o-rings if they aren't deformed, nicked, or torn. Give them a thin coat of PAG oil or Nylog Blue before installation.

Ok, so I did exactly that. I replaced the expansion valve with the Denso, replaced o-rings where I disconnected the lines and replaced desiccant. I vacuumed and filled by weight. I still get about the same readings...

1500 RPM
200-210 High
20-25 Low
80f ambient temp

I at my wits ends now to be honest... Do you have any other ideas ?

Thanks !

20-25 low should get the coil pretty cold. I would check the blend door or hot water in the heater core.

It indeed does, temp was alright even before I changed the expansion valve again. A/C is cooling enough, my problem is that it short cycles as soon as I rev up. 20 seconds engaged then 3 seconds off. At idle it's running constantly. Is this cycle considered short cycling ?

It's really annoying when I'm on the road because it makes the car judder. Also this can't be good for the A/C clutch.

[Tim]

I've not read through the thread entirely.

Have you checked the clutch gap?
You need to know what the pressure readings are when short cycling. Is tripping the low or high side of the system?

[gabton]

No, I haven't looked at the clutch gap. What kind of behaviour could that cause ? The compressor was replaced, I just installed it.

For the pressure readings, I would guess it's the low pressure. It triggers at the pressures i've mentioned previously (20-25psi and 200-210psi). I'm getting those readings at 1500RPM but as soon as it reaches those, it triggers off. This car has an evaporator temperature sensor but no low pressure transducer/switch.

Thanks

[Tim]

I watched your YouTube links.

13.4Oz to others saying 15Oz (AllData) confirms.

How much oil is in the system? It needs to be as close to OE as possible, no guessing.

If in a shop with a recalimer. I would add some refrigerant, R134a, of course. It looks low to be from a keyboard away.

[gabton]

I watched your YouTube links.

13.4Oz to others saying 15Oz (AllData) confirms.

How much oil is in the system? It needs to be as close to OE as possible, no guessing.

If in a shop with a recalimer. I would add some refrigerant, R134a, of course. It looks low to be from a keyboard away.

I don't know about oil to be honest. I had 2.7 oz in the compressor plus probably 1oz in the condenser and evaporator. When I flushed the evap again yesterday, I added the recommended amount per the service manual (evap 1 1/3oz, 1/3oz for the flushed line and 1/3oz desiccant). This is my error, I should have done it better but how would this affect the short cycling ?

I went to the honda dealership and they confirmed me it's 13.4 to 15 ounces. I added 15 3/4oz today. When I first did the repair, I also tried to add refrigerant slowly then taking readings. I probably overcharged the system by 8 ounces. Pressure was still dropping too low 15-25psi, which is why I guessed the expansion valve was bad.

[Cusser]

I think it's the temp sensor on the the evap core which senses temps close to freezing then disengage the clutch.

Disclaimer: I'm not an AC professional.

That said, could you TEMPORARILY jump/bypass that de-icer switch that goes into the AC evaporator, to see if that "opens" too often and disengages the AC clutch? On my 1988 Mazda truck there's two wires for my de-icer switch, and I would be able to connect those together to try similar.

[gabton]

I will try that, though I’m already pretty sure this switch is what triggers the computer to shutoff the ac. Its the only one I havent tried yet since its so far up the dash …. Idk if its a transducer though

[Tim]

The lines should meet in the middle, gray.

[JohnHere]

Tim said: 20-25 low should get the coil pretty cold. I would check the blend door or hot water in the heater core.

It indeed does, temp was alright even before I changed the expansion valve again. A/C is cooling enough, my problem is that it short cycles as soon as I rev up. 20 seconds engaged then 3 seconds off. At idle it's running constantly. Is this cycle considered short cycling ?

IMHO, that is not short cycling. It's more like normal operation to me. Short cycling would be 2 seconds on, 2 seconds off, repeating ad infinitum. And at idle, the compressor should run continuously, especially on a hot day. Again, normal operation.

If the vent temperatures are acceptable and the system cools the cabin sufficiently, why worry about how often the compressor cycles?

With such a small engine (1.8L), you're going to feel something whenever the compressor cycles. It's a tiny, low-horsepower, small-displacement engine. Put any kind of a sudden load on it, like the compressor engaging, and you'll definitely feel it. No getting around that.

Recently, I drove a late-model Toyota Highlander with a 3.5L 290-HP V6 engine. I never felt a thing when the compressor cycled in that car. But we're talking about an economy car versus a much larger luxury SUV with maybe triple the horsepower. Makes perfect sense.

I, too, watched the videos you posted, and I had a very hard time trying to discern the pressures. The reason for that is the Manifold Gauge Set you're using isn't sufficiently granular as far as the gauges themselves are concerned. For example, your low-pressure gauge has graduations in multiples of 50 PSI. A professional MGS would have graduations in multiples of only 10 PSI, making the gauge much more precise and easier to read. The same goes for the high-pressure gauge to a lesser degree, having multiples of 100 PSI when it should have multiples of only 50 PSI. Therefore, I would suggest replacing your existing MGS with a professional model having the proper graduations.