Automotive Air Conditioning Information Forum (Archives)

Provided by

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

Archive Home

Search Auto AC Forum Archives

overheating with AC on

aamir on Thu March 15, 2007 5:51 AM User is offlineView users profile

Year: 1994
Make: Suzuki
Model: Alto F8B
Engine Size: 800cc
Refrigerant Type: R143a
Ambient Temp: 45C
Pressure Low: 25
Pressure High: 250
Country of Origin: Pakistan

I have an alto with f8b engine 800cc. The car has only one cooling fan at the back of the radiator with the condenser in front. The problem with the ac is only in the day time when its very hot. The ac does not make the cabin cool enough. And after 30 minutes its almost not cooling at all. When the engine is turned off and given some time to cool down the ac starts cooling again and the same cycle continues. I have installed a new aluminium radiator but all is same.
Also my ac trips three to four times a minute and once the temp goes up in the day and fan comes on it wont' go off and with the fan running continously the temp creaps up and up. Also give me detailed information about fan and etc. like which car has those parts because here there are no such accessory shops. The only option is to go to the junk yard and ask about a specific model car part. Once again thank you very much.
I've got the readings as below:

engine timing 25
outside temp 47 C
downside pressure 25
upside 250
gas du pont R143a
fan 22amp (factory)

I placed a cloth in front of the condenser and it sticked there until i turned the ac off. Also i put foam between the radiator and cndenser left + right sides and top. However i didnt seal off the downside, should i seal it too. I tried the down pressure 35 and the upside went to 350 and the needle went to red in minutes and the car became powerless and bad cooling specially on CNG.

I have also remove the CB point and put a CDI in it. The alternator is replaced witha mitsubishi 65amp. The plugs are NGK iradium. Plug wire are high flow 1.0mm also exhaust is slightly modified the pipe is 2.2 inch with less restricted flow. Also if i switch to duracool will this help.

mk378 on Fri March 16, 2007 9:01 AM User is offline

It may be that the heater core is still working and fighting the A/C when the engine warms up. Disconnect or clamp off the heater lines. If the car has the typical Japanese manual control system, there should be a water valve operated by a cable from the temperature dial on the dash. Make sure the valve closes fully with the dial on full cold.

There is still a problem with the engine cooling if the fan can't keep it in the normal range. Make sure the coolant is completely full. Again not knowing that specific car, I assume it has a conventional radiator under pressure but reservoir tank at atmospheric pressure system. A problem with the radiator cap can cause the coolant to migrate out ouf the radiator and into the reservoir tank. Thus the tank is full but there isn't enough in the radiator. With the engine cold, remove the radiator cap and check that it is full to the top. I assume you've already replaced the thermostat; you could also try running the car with no thermostat for a while.

Finally in hot weather the A/C should not trip on and off unless it is really cold inside the car. Measure the pressures when this is happening. Too much high side pressure could be inadequate condenser cooling, overcharged with refrigerant, or air in the system. Air in the system means someone opened the system, then refilled it without using a vacuum pump to take out the air first. The only way to get rid of the air is to remove all the refrigerant/air mixture and pull a vacuum, then recharge.

Edited: Fri March 16, 2007 at 9:06 AM by mk378

aamir on Sat March 17, 2007 2:51 PM User is offlineView users profile

Thanx dear, I'll remove air out of system and then give u the results.

UK Tech on Sun March 18, 2007 2:26 PM User is offline

If it's overheating even with the fan running, and everything else checks out ok, then your radiator is probably blocked. You need a new one my friend.

aamir on Mon March 19, 2007 7:41 PM User is offlineView users profile

Thanx 4 the reply.

By the way if i put a pusher fan in the front would it help bringing down the temp ? ( the rad and cond are right in front of each other )

mk378 on Mon March 19, 2007 10:29 PM User is offline

The test to see if you need more fan is to test-drive on a level road at a steady speed of at least about 60 km/h. If everything stays cool due to the blast of air from the car's motion, then yes more fan will help.

aamir on Tue March 20, 2007 8:09 AM User is offlineView users profile

Thanx 4 reply.

I'll take my car on the motorway to test.

Also if i put an engine oil cooler will it help bring down the temp.

VetNutJim on Mon March 26, 2007 9:50 PM User is offlineView users profile

'73 Cheyenne 355 TPI

VetNutJim on Mon March 26, 2007 9:57 PM User is offlineView users profile

my ac trips three to four times a minute and once the temp goes up in the day
This and your LOW SIDE PRESSURE of 25 PSI may indicate the system is cycling via the LOW PRESSURE SWITCH.

The evaporator may also be freezing because of:
When the engine is turned off and given some time to cool down the ac starts cooling again

There are many folks on here with more experience than me but those statements lead be to 'think' The System Is Low On Refrigerant

'73 Cheyenne 355 TPI

Bucky on Fri August 31, 2007 3:22 PM User is offline

I have the same overhearing problem with the AC on.
I have a 1982 Toyota Celica. Converted to R134a in 2004. On hot days the AC works just fine but the Engine overheats in about 15 or so minutes with AC on (even on the hwy at 60 mph).
I replaced the radiator last year and flushed the coolant again this year. I just had the AC coolant charged up by a good technician, thinking that was the problem. I just cleaned the condensing unit coils and radiator coils to remove any crud/dirt, but no change after any of the above. My technician suggest that there may be clogging in the radiator, as he typically sees this as the overriding problem.
I notice that the AC condensing coils are somewhat dinged up and will try to "comb" them out. (probably not much effect here).
Also, I will change the radiator out again (thanks to the lifetime warranty) and change the T-stat. I'll do all that, but I think their may be something causing the AC condensing unit to become so HOT that the radiator behind also overheats. What's happening there? PS I don't' see this problem if the outside temp is 75-80 degrees, only on 95+ degree times of the day.

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.