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System Cycling

chillin on Wed June 10, 2009 11:16 PM User is offlineView users profile

Year: 2002
Make: chevrolet
Model: 3500 van
Engine Size: 5.7
Refrigerant Type: 134a
Ambient Temp: 88
Pressure Low: 31
Pressure High: 215
Country of Origin: United States

This van had ac delco reman comp. accl. o.t. low press switch and they so called Flushed system.Buddy then pulled vacuum for 1 hr. charged 32 oz 134a and 8oz pag oil . High side pressure went to 400psi.He then changed the condensor and added 2oz oil to replace oil poured out of plugged cond.changed a dirty o.t.vacuumed and recharged.At idle low side 31 high side 215 then at 1500 rpms system would cycle low side off at 21 on at 42 high side no higher than 225 every 30 seconds.Is this normal cycling or does this compressor seem damaged?wish he would have changed that condensor in the begining.Thanks for any replies.

chillin on Wed June 10, 2009 11:23 PM User is offlineView users profile

134a was charged by weight. thanks again

bohica2xo on Thu June 11, 2009 3:27 AM User is offline

Much would depend on the cabin fan speed during the 1500 rpm test.

Cabin fan on highest speed, doors open - that is a full load test above 80f ambient. If the system is cycling under those conditions, your evaporator is likely plugged up on the air side.

If the fan was on the lowset speed, then yes cycling would be expected.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

chillin on Thu June 11, 2009 8:55 AM User is offlineView users profile

Volume of air did not seem that bad on max air doors open fan on high.Will look at evap. face.This is a work van lots of abuse. Thanks Bohica

chillin on Sat June 20, 2009 11:48 PM User is offlineView users profile

Found leak in evaporator and changed Added same amount of oil that drained out.Vacuumed and charged by weight 32 oz 134a. At 90 deg. windows open blower on max 1500 rpm it is still cycling. when at idle system cools fine but when increasing rpm low side falls quickly until it reaches 21 psi low pressure switch seems to be working high side 220. with a new evap Iwould not think it would be an air flow issue. Could this compressor be bad it is a reman?

Chick on Sun June 21, 2009 6:01 AM User is offlineView users profile

Your compressor is pulling down, and pumping pressure. Thats what they do.. So I'd say the compressor is not the problem. Unplug and jump the cycling switch, if the low side keeps going down, and even into a vacuum, you still have a blockage. When you changed the evaporator, did you check the O tube again??

-------------------------
Chick
Email: Chick

---------------------------------------------

Freedoms just another word for nothing left to lose

Edited: Sun June 21, 2009 at 6:02 AM by Chick

chillin on Sun June 21, 2009 6:15 AM User is offlineView users profile

Thanks chick! I will try that.I was looking at the 134a capacity sticker it says 32 oz but on an 2001 van capacity says 48oz wondering if sticker could be wrong? tenth number on the vin says 2. Will try unplugging the low pressure switch and see what I find.

chillin on Sun June 21, 2009 6:21 AM User is offlineView users profile

O tube did not look that bad but will put in a new one.will post back with more details later thanks for all your help.

Chick on Sun June 21, 2009 6:48 AM User is offlineView users profile

Quote
Originally posted by: chillin
Thanks chick! I will try that.I was looking at the 134a capacity sticker it says 32 oz but on an 2001 van capacity says 48oz wondering if sticker could be wrong? tenth number on the vin says 2. Will try unplugging the low pressure switch and see what I find.

That could just be the difference between front air and dual air, always go by the sticker.. I cheked and front air only lists 32 ounces.. or 2 pounds

-------------------------
Chick
Email: Chick

---------------------------------------------

Freedoms just another word for nothing left to lose

chillin on Sun June 21, 2009 9:25 AM User is offlineView users profile

Problem solved! Did check o tube put in a new. pulled a good deep vacuum and charged by weight 32oz by sticker and it still cycled at 1500 rpm.Started adding more 134a and charged 48 oz. 80 deg ambient at idle low 32 high 190 at 1500 rpm 26 low 230 high 44 deg vent temp no cycling.Thanks to all that helped. HAPPY FATHERS DAY!Remember this is the site for quality parts and no other site responds with help like this one!

daman on Mon June 22, 2009 10:50 AM User is offlineView users profile

Quote
Originally posted by: chillin
Problem solved! Did check o tube put in a new. pulled a good deep vacuum and charged by weight 32oz by sticker and it still cycled at 1500 rpm.Started adding more 134a and charged 48 oz. 80 deg ambient at idle low 32 high 190 at 1500 rpm 26 low 230 high 44 deg vent temp no cycling.Thanks to all that helped. HAPPY FATHERS DAY!Remember this is the site for quality parts and no other site responds with help like this one!
so the factory sticker was off? you needed to add more huh??

same here with my '99, added 32oz and wasn't enough needed more to keep the cycleing off. why is the factroy amounts not right on these trucks? anyone.



-------------------------
'00 Pontiac Sunfire 2200 I4 SFI
'99 Chevy 4x4 Z-71 5.7 Vortec v8 CPFI
'97 Chevy 4x4 6.5 Turbo Diesel 2500
'95 Pontiac Grand Am GT 3100 v6 SFI
'88 Chevrolet Camaro IROC 5.7 TPI(49,000 original miles)

Edited: Mon June 22, 2009 at 10:51 AM by daman

CCWKen on Mon June 22, 2009 11:45 PM User is offlineView users profile

When in doubt, check the bulletins. It wouldn't be the first time under hood OEM stickers were wrong.

-------------------------
Ken Kopsky

Custom Car Works
"Rules are for the guidance of wise men and the obedience of fools."

bohica2xo on Tue June 23, 2009 1:33 AM User is offline

Chillin:

Thanks for the update. I will add this to my notes - thanks!

I checked the TSB's, and there are none for this vehicle regarding undercharge / label errors.
Interesting, the dual A/C units show a spec of 56 ounces of refrigerant for this vehicle, and 32 ounces for front only A/C. I did not find 48 listed anywhere. I wonder how badly undercharged some of the dual units might be...

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

daman on Tue June 23, 2009 9:30 AM User is offlineView users profile

its not just dual units,like i said my '99 was off too,32oz's (2lbs)was not enough and i even put in
a few extra oz's to make up for what was in the hoses lost.

-------------------------
'00 Pontiac Sunfire 2200 I4 SFI
'99 Chevy 4x4 Z-71 5.7 Vortec v8 CPFI
'97 Chevy 4x4 6.5 Turbo Diesel 2500
'95 Pontiac Grand Am GT 3100 v6 SFI
'88 Chevrolet Camaro IROC 5.7 TPI(49,000 original miles)

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