Automotive Air Conditioning Information Forum (Archives)

Provided by www.ACkits.com

We've updated our forums!
Click here to visit the new forum

Archive Home

Search Auto AC Forum Archives

Nedd AC help/advice Pages: 12

a94civicex on Sat July 24, 2010 12:12 PM User is offline

Year: 1994
Make: honda
Model: civic
Engine Size: 1.6
Refrigerant Type: r134
Ambient Temp: 86
Pressure Low: 30
Pressure High: 300
Country of Origin: United States

Need help. AC doesn’t blow cold. Below is the information I’ve gathered.

Vehicle: 1994 Honda civic ex. 1.6, R134 factory system
Outside Temp: 86
Humidity: 70
Static Pressure: L=105 H=100
Idle Pressure: L=48 H=250
Pressure at 1500 RPM after 10 minutes: L=30 -35 H= 300 – 320; temp at vent 64
Doors open, fan on high, Re-circulate on
Compressor on, condenser fan on
Low pressure line : cold
High pressure line: hot

Does anybody have any idea what could be wrong? Thanks

Cussboy on Sat July 24, 2010 12:21 PM User is offline

At glance, numbers don't look horrible, maybe a little high.

1. Have you done anything to the AC system recently except read pressures?
2. Are both electric fans running full time when the AC is switched on?
3. Is any heat getting mixed in, have you temporarily bypassed the heater core?


Edited: Sat July 24, 2010 at 12:25 PM by Cussboy

bohica2xo on Sat July 24, 2010 12:27 PM User is offline

At 86f ambient that is some crappy condensor performance.

Check the fan(s) for proper operation, and clean the condensor thoroughly. Use a strong surfactant like Simple Green or ZEP Orange. Spray it deep into the fins of a cold condensor, and let it soak for a few minutes. Hose it out. Repeat. Use a low pressure hose. If you use a powerful water stream you risk bending the fins on the condensor.

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.

a94civicex on Sat July 24, 2010 12:33 PM User is offline

. Have you done anything to the AC system recently except read pressures? NO
2. Are both electric fans running full time when the AC is switched on? yes
3. Is any heat getting mixed in, have you temporarily bypassed the heater core? no

a94civicex on Sat July 24, 2010 12:53 PM User is offline

Quote
Originally posted by: bohica2xo
At 86f ambient that is some crappy condensor performance.



Check the fan(s) for proper operation, and clean the condensor thoroughly. Use a strong surfactant like Simple Green or ZEP Orange. Spray it deep into the fins of a cold condensor, and let it soak for a few minutes. Hose it out. Repeat. Use a low pressure hose. If you use a powerful water stream you risk bending the fins on the condensor.

Condenser is clean as a whistle

B.

ice-n-tropics on Sat July 24, 2010 3:31 PM User is offline

Sanden scroll comp is OK
Possibilities:
1) hot engine air recirculating back into the condenser.
2) Partial internal cond blockage
3) reheat of refrigerated air
Time to water mist the condenser and recheck
Also try doors closed (as well as open) due to high humidity
hotrodac

-------------------------
Isentropic Efficiency=Ratio of Theoretical Compression Energy/Actual Energy.
AMAZON.com: How To Air Condition Your Hot Rod

bohica2xo on Sun July 25, 2010 2:17 AM User is offline

320 psi @ 86f is the problem. a BIG problem.

If the condensor is clean all the way through, then mist some water on it. It is either not getting any airflow, or some of the serpentine channels are blocked.

That condensor had very high fin density, and can appear clean on the face.

If misting water on it drops the pressures quickly, try a road test. Tape the gauges to the windshield & driver 45 t o50 mph @ 1500 rpm or higher. Post the pressures.

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.

a94civicex on Mon July 26, 2010 4:18 PM User is offline

Cleaned the condenser fins and retested. Below are the results.
Outside Temp: 92
Humidity: 75
Static Pressure: L=100 H=100
Idle Pressure: L=43 H=160
Pressure at 1500 RPM after 10 minutes: L=25 H= 325 – 340; temp at vent 60
Sprayed water on the condenser: L=28 H= 250; temp at vent 60, pressure returned to above
Doors open, fan on high, Re-circulate on
Compressor on, condenser fan on
Low pressure line : very cold
High pressure line: very hot
Does anyone have a theory. The black high pressure hose felt like coolant was moving through it (pulsating).

mk378 on Mon July 26, 2010 5:17 PM User is offline

I agree with bohica, high side is too high. Possibly overcharged with refrigerant or oil, or refrigerant contaminated with air. I don't see anything about evacuating and recharging to factory spec.

Pulsation of the high side will occur with a scroll compressor. They have a "once around" action so the pressure normally comes out in pulses.

On the 1500 rpm test, the compressor should start to cycle on evaporator temperature. Then the air leaving the evaporator should be about 40 F. If the air at the vents is warmer, check for reheating. Very common for the heater valve to not close fully.

Edited: Mon July 26, 2010 at 5:18 PM by mk378

a94civicex on Mon July 26, 2010 5:38 PM User is offline

I'll take it to a shop (if I can find a good one) and have it evacuated / recharged to factory spec. I'll report back . One shop told me I need a new compressor and all the things that go with it ($1000).

bohica2xo on Mon July 26, 2010 6:53 PM User is offline

The compressor is fine if it will push 300+ psi.

The water test shows a weak response - it is just not getting rid of the heat. An airflow issue would usually show a huge drop with a water mist test.

If you don't know the history of the car, it may have had too much oil added to the system at some point. Or it may have several clogged passages in the condensor. With a 15 year old car it is hard to get an accurate history.

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.

fasto on Tue July 27, 2010 12:42 PM User is offline

Quote
Originally posted by: a94civicex
Pressure at 1500 RPM after 10 minutes: L=25 H= 325 – 340; temp at vent 60

Something is getting cold with that low side pressure! You need to check for reheating from the heater core if your vent temp is only 60 DegF. Clamp off the heater hose, bypass the heater core, check the heater control lever, etc.

bohica2xo on Tue July 27, 2010 12:50 PM User is offline

Actually, that is the problem - nothing is getting cold.

The 340 psi refrigerant is about 160f. There is no way to recover much heat with refrigerant carrying that much heat to begin with.

The brief excursion to 28 x 250 with the water spray probably produced some cooling - but not enough to offset the heat in the cabin equipment, so the vent temp did not move appreciably.

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.

a94civicex on Fri July 30, 2010 9:11 AM User is offline

Clamped off the heater hose. Same outlet temperature

1stbscout on Sat July 31, 2010 1:19 AM User is offlineView users profile

Sounds to me like a bad/stuck expansion valve or moisture in the system. High - high side low low side and little cooling.

a94civicex on Sun August 01, 2010 10:16 AM User is offline

I'm getting ready to vacuum/recharge the system. Can someone tell me what the proper pressure readings (HI - LO) should be for this vehicle or point me to a chart for this vehicle ( so I know when to stop charging---- owners manual says the system takes 17.6 - 19.4 oz.). I looked at chart that was in the service manual but it didn't make any sense. Appreciate all the help/response
It's 92-95 degrees, 70 -80 humidity.

mk378 on Sun August 01, 2010 11:10 AM User is offline

Charge it by weight. Anywhere between 17.6 and 19.4 oz is proper. There is no need to optimize within that range. Try to get closer to 19.4 to accommodate any slight leakout later.

a94civicex on Tue August 03, 2010 3:08 PM User is offline

I vaccumed the system for 30 minutes (-30 on the guage). Turned off the vaccum/guages for 30 min. (still -30). Vaccumed for another
30 min. Turned off vaccum/guages for 30 min. (still -30.) Recharged with R134 (approx 21 oz by weight).

Guage readings: IDLE: L22 H235 (CONDENSER FAN ON)
1500RPM: L25 H290 (CONDENSER FAN ON)
Ambient Temp: 101 -103
Humidity: 75
Took a test drive on the X-way. Vent temp 48 -50 degrees, Fan on high, Re-circulate on (A lot better than before).
Is this Temp about right for the conditions or is there still something amiss?? thanks

98audiA4 on Tue August 03, 2010 3:39 PM User is offline

FWIW i had a 93 civic a year ago for a couple years and i tried 2 different evaporator switches and both cycled off with a vent temp right at 50. the only way i could get cooler air was by wiring in an override switch and keeping an eye on the thermometer i left in the center vent.

if your system is cycling (clutch shutting off for a short period of time) and the temp stays pretty solid at 50 then i'm gonna say you have the same issue i had.

a94civicex on Tue August 03, 2010 4:03 PM User is offline

Compressor is not cycling on and off.

jglanham on Wed August 04, 2010 5:16 PM User is offline

101-103 degs. ambient, 75% humidity, 48-50 degs. vent temp.
53 degs. drop from ambient at that humidity level isn't that bad.

-------------------------
johnl

Edited: Wed August 04, 2010 at 5:19 PM by jglanham

a94civicex on Thu August 05, 2010 9:28 AM User is offline

Bohica2x0, What do you think?????????????

bohica2xo on Thu August 05, 2010 10:08 AM User is offline

That looks more like it should.

That is a first year 134a vehicle, and Honda does not tend to put much A/C in a car to start with. In another thread here someone posted the factory performance chart for a 2000 Civic. According to that chart, your 1994 is performing better right now than the 2000 model. They say a vent of 68 to 75 degrees would be "normal" for those conditions.

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.

iceman2555 on Thu August 05, 2010 10:32 AM User is offlineView users profile

The posted temp and humidity equates to a heat index of app. 165 degrees.
This posted vent temp is actually very good. Expectations should be a temp drop between the HI and vent of 45-55 % is acceptable.
Not sure what vent temps are expected...but seems this system is working well. Also at this temp range...it is quite possible the system will not cycle.
Side note: Received a compressor back from a recognized retail repair facility....yep it was a warranty return.....returned for....get this....the compressor would not cycle......air gap is correct....clutch amp is right on the money.....driver engages and disengages as it should........compressor pumps....all is well....but the darn thing simply would not cycle......canyabeliveit!!!!


-------------------------
The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

bohica2xo on Thu August 05, 2010 11:10 AM User is offline

Ice, I can believe it. That CCOT crap has been around so long now, we have a generation that has seen nothing else. They seem to think the "cycling" is what makes it work...

I had a kid at a car show ask me how to make his system cycle - he had a V7 in an S10. He was convinced it did not cool as well because it ran all the time.

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.

Back to Automotive Air Conditioning Forum

We've updated our forums!
Click here to visit the new forum

Archive Home

Copyright © 2016 Arizona Mobile Air Inc.