ac compressor clutch cycles on and off?

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ac compressor clutch cycles on and off?

Postby musik » Sat Feb 28, 2009 7:36 pm

ac compressor/clutch cycles on and off? 1998 chevy s-10. i just charged the system with 2lb of 134a. new compressor and orifice tube.

cycles every 6-8 seconds?

GUAGE READINGS:
ENGINE OFF:
Low 60 psi
High 60 psi

ENGINE RUNNING WITH AC ON MAX:
Low 45/50 psi compressor turns on, 25 psi compressor turns off.

High 75/80 psi compressor turnrns on, 115/120 psi compressor turns off.

when i place my hand on the suction line coming from the compressor its cold and the dischargege side is hot.

Temp is reading 40 deg consistantly.
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Re: ac compressor clutch cycles on and off?

Postby Tom Greenleaf » Sun Mar 01, 2009 12:11 am

2 lbs of 134a is fine for the pickup S-10.

Static temp suggests it's only 61-62F ambient temps out and system would cycle normally. That's a bit cool out for performance testing but the #s so far are consistent with the low temp outside.

Hope you spun some oil in new compressor and added some.

I'm guessing your 40F observation was vent temps? If so that's the limit of what it should ever do really and would shut down compressor around there.

So far this seems normal with the short cycling and at cool/cold temps ambient (like below 75F) I don't suggest forcing compressor to stay engaged in any way,

T
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Re: ac compressor clutch cycles on and off?

Postby musik » Sun Mar 01, 2009 3:59 pm

Dont know how you knew, but yes it was exactly 60 deg when i took these readings.

yes the temp was takin from the vent.

I did put 4 oz of pag 150 oil in the compressor and spun it by hand about 10 times. also put 4 oz in the accumulator (silver can). it was really tuff spinning the compressor by hand!

it just didnt seem right for the compressor to be turning on and off like that and i wasnt sure so im seeking advice, thank you for helping.

list of what i did.

new compressor with clutch
new accumulator (silver can)
took ALL hoses off and replaced all O-rings
replaced the orifice tube
flushed the thing that attaches to the silver can, sorry i dont remember the name but its in the firewall.
took off the "wetline" and flushed it. only because the old orifice tube was so filthy with debrits and metal shavings on it.
added oil to the comp. and accum. 4 oz of pag 150 to each.
then when everything was put back together i vacumed the system to -25 for 20 min (all my compressor could keep up with, i used a venturi pump), and then let it sit for an hour. i lost no vacume.

then i hooked up the 134a cans and charged it. it took forever, atleast 1.5 hr to get 2.5 cans in the system. the instruction video and cans said do not hold upside down when charging, is this true?? because i you tubed recharging an ac and all the guys there are charging there system with the cans upside down aggitating them at the same time.??

so i just did it with the cans upright with a little aggitation through the process. it was an all day process to do this job, it was my very first ac job and i dont know diddly about ac's.! im just trying to make sure i did everything right.!
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Re: ac compressor clutch cycles on and off?

Postby musik » Sun Mar 01, 2009 4:07 pm

also i forgot to add yesterday after posting here i switched the ac setting from max ac to just ac and the compressor seemed to cycle less then eventually after about 2-3 mins it stayed on and the vent temp went to 47-48 deg consistantly.

is this normal.?
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Re: ac compressor clutch cycles on and off?

Postby Tom Greenleaf » Sun Mar 01, 2009 4:32 pm

I can't speak for what you saw as a demo on YouTube but it obviously didn't mention you should have waited for warmer temps and you should heat the little cans as they dispense with WARM water. AN HOUR AND A HALF! You no doubt leaked more than went in an now have no clue what weight of charge is in it and really should start over!

You need to purge even the tad of air out of lines of even can taps and charge only into a well held full vacuum or it's going to be trouble if not now it will down the road.

This vehicle states underhood as most do what the weight of the charge should be. I found 2 lbs on a chart - use your info for the exact vehicle. From a vacuum when using 12oz cans the first would usually go in as a liquid no problem without the engine running. Then you would force the compressor to suck in the remainder - guess YouTube didn't go that far and forcing a compressor at 60ishF is risky biz which is why I suggest waiting for warmer ambient temps.

The reason I knew the temp is because you listed the pressure. There's an exact chart of what pressure will be seen at a given temp. That's just a static pressure and only means there's some to read. It is NOT an indication of how much until it's way too low vs the temp and that's another story.

Without equipment you really shouldn't be charging or forcing compressor as said to complete the charge at lower temps ambient,

T

Again - It's too cold out at 60ish F for performance testing. Compressor must be staying engaged to really take pressures and temp outputs. It can be forced but not when that cold out.

More: You said 2.5 cans went in. How much did each can hold? Charts show 32oz system total - VERY important to be as close to exact as possible to that. +/- two- three would be operational IMO. That's enough margin for error no more!

I really suggest you have whatever is in there recovered and left in a state of vacuum for you to charge again with an exact known weight which will work and go in even with little cans in a few minutes for the whole deal!

Note: The upside/downside can thing is about liquid or gas coming out of the can. You don't want to rush a liquid at a running compressor as it would choke on liquid and you can't compress liquids - you can compress gasses. Refrigerant is either gassous or liquid based on temp + pressure it under.
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Re: ac compressor clutch cycles on and off?

Postby GM Tech » Sun Mar 01, 2009 8:05 pm

If your low side charge port is on the accumulator, it is quite alright to charge as a liquid- since the accumulator will separate the gas from the liquid for you. The compressor will only suck in the gas then....as designed.
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Re: ac compressor clutch cycles on and off?

Postby musik » Mon Mar 02, 2009 5:59 am

They are 12 oz cans. yes the low side is mounted on the accumulator.

how would it have leaked out when charging?

-25 psi isnt enough.? my guage set only goes to -30 psi.? i vacumed it at -25 psi, like i said thats all my comp would handle for extended periods of time.

your saying have it recovered..>
ill buy a vacum pump if thats what it takes to get a -30 psi vacume, not a big deal. charge the system mid day when temp is highest, and put the cans in warm water while im charging the system or before?

the cans got quite cold while charging.

on the can it said it could take up to 15min for each can to dispense fully.
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Re: ac compressor clutch cycles on and off?

Postby Tom Greenleaf » Mon Mar 02, 2009 7:02 am

"the cans got quite cold while charging.

on the can it said it could take up to 15min for each can to dispense fully."

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Just read a can I keep right at the puter - says all kinds of stuff but not 15 min! Don't take it wrong - there's enough bad info out there to fill the Grand Canyon!
~~~~~~~~~~~
As says on a Johnsen's 12oz - "134a Refrigerant" - For 134a A/C systems only (that's nice)

DO NOT CONNECT CAN TO HIGH PRESSURE SIDE OF SYSTEM OR ANY SYSTEM WITH A PRESSURE HIGHER THAN 170 PSIG. This may cause can to burst - resulting in serious personal injury. Start engine and set air conditioner controls for maximum cooling. Check system with gauge to determine pressure (suction) service port. Charge system only through low pressure side. Hold can upright to charge gas. Use only required amount.
~~~~~~~~~~~~~~
That verbatim from their can not my words.

OK: The reason I'm worried is it took so long and you no doubt (I'm guessing) didn't have compressor jumped to stay engaged to suck in the contents as you would - again when warmer really helps. You usually can just warm the little cans with your hands or if needed have a pan of warm water ready (warm not piping hot) as they will get cold as they deliver their contents. Pretty much the pressure is going from highest to lowest so you need to make the can higher pressure than the vehicle. Temp is close to psi by coincidence with 134a and others too. I have a bunch of nice solid brass can taps and half of those failed to seal properly or dispense properly when new! I worry about the quality of some of the junk out there. Mine are run thru a gauge set as well so I'm watching both pressures and take in and out temps while charging.

The little cans are a pain but I find them for literally a buck now and then at end of season and have bought them all sometimes as it's real product just a hassle vs larger container - usually a 30 pounder.

It may be ok if you are pretty sure no air got sucked in thru leaky connections and it can be charged by pressures when you have a steady higher ambient temp to work with. I'm worried for you right now that it could have too much air introduced and the weight of charge is somewhat unknown. It needs to be close and until system is working hard with lots of observations you really can't tell the performance when cold out. Again - it shouldn't be forced to stay engaged when cold outside or where you are working.

The vacuum: 29.92Hg is a full vacuum at sea level. If your gauges are accurate and you could only pull 25Hg (minus side is measured in inches of Mercury) that's really not all that good. Air has moisture which is the enemy and 25Hg at sea level still isn't a full vacuum which by nature is void of air. {{Air won't compress and moisture can cause acids to build up or frost inside}}

Do you know your altitude? You can call it a full vacuum reducing the #s by 1Hg for each 1,000 ft of elevation +/-.

I can look up your altitude or you can with Google Earth!

Check your vacuum pump against your own gauges without the vehicle. You should be able to plug off your gauges while hooked up and read the capability of the pump. It could also be a gauge inaccuracy??

It's not legal to purposely vent refrigerant so I can't suggest doing that. If you don't have recovery/recycle equipment you are supposed to have any known charge recovered. Give that away and still pay someone or get a machine.

You may vacuum a system devoid of refrigerant to a vacuum. Trace amounts lost are acceptable.

More: There's air in hoses if exposed to atmosphere too. When hooked up to charge source you normally let a spit of refrigerant out of line to know it's purged of air before hooking up. No body's cans or equipment details that minor but real concern especially when using the little cans as you are switch from one to the next instead of one container.

Still More: If the charge is really low now it will cycle on and off with defrost request or mix of anything using defrost. Low charge doesn't move oil well to keep compressor lubed and could hurt it. IMO - if unknown - unplug/disable compressor till it's known ok to operate.

Don't worry so much about the liquid vs gas charging as GM Tech said you are adding to an accumulator which is large and far enough away from compressor. Liquid (can upside down) is just faster. It's not a problem on a warmer day either way but better to use gas only for the finish.

Charge weight is important. You can weigh cans with an accurate scale with any hose or tap so you know how much or a partial one you've used or is left. The can taps frequently won't hold a part can forever when just shut if you leave it for weeks or months for any future use it may be lost.

Egad - Sorry for the "verbose" reply. I only want to see you get this working properly such that it will last its best. Ask away as I'm good at confusing things too :roll:

T
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Re: ac compressor clutch cycles on and off?

Postby musik » Wed Mar 04, 2009 9:54 pm

No thats no problem i appreciate your help!

ill just have the system recovered when i get plates this week.

ill buy a real vac pump and start over. i live in las vegas

i wasnt lying about the johnsons can heres a pic.


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Re: ac compressor clutch cycles on and off?

Postby Tom Greenleaf » Wed Mar 04, 2009 11:57 pm

Oh - I surely believed you. What I can't believe is the lack of good info with the stuff they sell out there - #1 being the low side only canned fix it all in one blast with a gauge, bazooka bubble gum and who knows what's in it stuff and the wild claims of "Up to 40% cooler" ---- junk like that. Duh - of course any system not working at all will possibly be some percent cooler before it blows up - laugh - not really.

Have friends in Vegas on Glorietta ln! You need this as perfect as possible from what I hear from them! I've fixed up one of their cars over the phone - had a place out there leave it in a vacuum and we did the charge live on phone - daughter and wife team running back and forth getting warm water - must have thought we were nuts but it worked out perfectly.

Good luck with it,

T
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