Hello!

I’ve been trying to get my A/C to work. I tried doing the breadclip/zip tie clutch fix, but the compressor still cycles. However, after the fix the click of engagement is much quieter. Anyway, the car doesn’t seem to want to take any more refrigerant. When the compressor is engaged, the pressure gauge reads 18-20 before it cycles back off. Occasionally, it will stay engaged and the pressure will climb to maybe 23. Then it cycles off and resumes cycling. The metal line coming from the bottom of the big can is cold with condensation on it. The dark, rubber hose coming from the top of the big can is ambient temperature.

Is there a blockage somewhere? Could I find the evaporator and give it a good thwack to knock stuff loose? Is there something I could add to get the clog out? Is it something else altogether?

Many thanks!

Connect your gauge to the low side port (next to the big can) with engine off and stone cold. Do this first thing in the morning or late at night. The pressure should read somewhere between 80 to 100 psi according to ambient temp. If it reads lower than those, total system charge is low.

Low charge could be the cause of your rapid compressor cycling.

Amarin.

I checked the pressure on the port by the drier (big can), and it read about 75 before coming off. On the flip side, it’s not taking any more refrigerant. Is there a blockage?

One thing for sure your system is low on refrigerant. Need to top it up. Its difficult to tell whether there is blockage or not with low refrigerant. With that low side pressure (18 - 23 psi) when AC is ON, your system should be able to take in more refrigerant unless your refill can is nearly empty. For the refrigerant to get in the pressure in refill can should be more than 23psi (i.e more than the sytem's low side pressure). Could try immerse the can in warm water or get a full can. I'm assuming you're using the small hand-held quick refill can.

If still no any cooling even after about half-can refilling then there is blockage. No you can't knock the blockage out because it would mostly be at the orifice tube's filter mesh. Something sludge-like substance. Need to evacuate system and replace orifice tube.

In short when system charge is low there wouldn't be any cooling because not enough refrigerant to absorb heat@evaporator to release it out later@condenser. When refrigerant is enough but still has no cooling its because reduced refrigerant flow at orifice tube due to blockage.

Amarin.

It’s a totally full can. It likely a blockage I’m thinking. I’ll try the warm water method first.

I know the system has to work since the metal line below the can is ice cold.

"the metal line below the can is ice cold"

--> if at any time when turning ON the AC you see frost (i.e. ice formation) at that metal line, then there IS blockage. Confirmed.

Amarin.

Aw man! Lame. Haha

I reckon, though, I could just evacuate the system and undo the compressor lines to get to the sediment filter thing, right? Or would evacuation suck all that junk out?

Or do I just need a whole new system?

"I reckon, though, I could just evacuate the system and undo the compressor lines to get to the sediment filter thing, right?"

--> Yup. Something like that. But if you're doing this the first time there a risk of destroying the orifice tube if it stays stuck in the line. See the FAQ on how to get it out. You could use small pick (with a blunt end that could fit into the line) to pull the tube out. Avoid scratching the inner wall of the line. Or use orifice tube puller tool sold at many online stores. The tube is located in the condenser line to evap, not in compressor line to condenser. It should be in that metal line under the can.


"Or would evacuation suck all that junk out?"

--> Nope. That sediment is a kind of sludge - sticky thing. No amount of evacuation could dislodge that. You could, however, use carb spray to clean the sediment off the filter mesh if you manage to get the tube out intact. Also use some kind of small needle/wire strands to clean the small orifice within the tube itself.

Amarin.

Thanks for your help!

Hi,

I might like to add to the prognosis that the orifice tube is plugged.
The high side pressure side would be going very high the more it gets filled up.
That could take a very long time to get filled up due, to the very short cycling going on, because of the restriction.

If you open up the line between the condenser and the evaporator, as it has a two nut coupling, you will find the orifice tube in there. It can or will be tight in there, so twist lightly back and forth while pulling on the colored plastic screen assembly.
The color helps to identify the size of the orifice.
If you find a fine gritty oil soaked substance in the screen that will be the blockage.
You might get by with cleaning it but it's not recommended and they are only about $7.00 in USA dollars.

On these older cars, it can be most likely that the desiccant package or bag could have busted open and the desiccant has dispersed.
This bag is in the big aluminum can that will have to replaced as a whole unit. They cost around $20.00 in USA dollars.
Compare the type of threads on the cans fittings carefully and their orientation to your systems connections.
It's not unusual that hoses change from vendor bidding on contracts to match other suppliers contracts with design alterations.

I suggest cleaning out the whole system with a flush as that stuff is everywhere and hopefully has not damaged the compressor.

There has to be a price to be paid to stay cool!
Imagine what a refrigerant free system, using big semiconductors, might be as an option $$$ on the electric cars of the future.
Be happy with a $50 - $300.00 do It yourself bill. Whoops that's on the 240's.

Phil

Thanks! Very helpful. I think my biggest expense is going to be the evacuation and recharge. I don’t have a vacuum pump.

If the pressure INCREASES the longer the compressor runs then it sounds like you’re trying to service it through the high pressure port.
--
Current rides: 2005 Volvo S80 2.5T, 2003 Volvo V70 2.4NA, 1973 Volvo 1800ES (getting ever closer to road worthiness)

I’m doing it at the port next to the receiver/drier (big can). I should note the ac is not cold.