engine temp goes up with air con W124

[syeddanial]

Hi everyone,

I am Danial working in Malaysia but a UK resident. I have a E280 1994 W124 which is a Malaysian local spec and recently, i sent my car for repairs that includes changing the air-con compressor unit. The problem is now when my aircon is on, my tempreture is hovering below and above the bar before the 120 bar temp. I believe the bar before the 120 bar must be the 90 temp reading bar. Sometime, when i go up the hill and especially with 3 people on board including myself, i goes inbetween the 90 and 120 temp bar and getting closer to the 120 bar, though if i turn the air-con off, the temp goes down to between 80 bar to the 90 bar temp. My mechanic informs me that there might be a bearing problem on the compressor which i bought as a overhauled unit. Has anyone's has opinion on this on what this problem might be?
I have 3 fans, 2 small fan and 1 large fan and all are working ok. The 2 small fan has been recently installed as a new unit.

 

[panason1c]

I'm no expert on air-con but i do believe that 'overcharging' (too much gas/oil) the system will cause the compressor to excessively load the engine. When you turn on the air-con with the engine at tickover does the engine slow down noticably?

 

[grober]

Does sound as if your problems are coming from the air conditioning unit. Perhaps it would be best to take it back to the garage it was repaired to get checked out. Were any other repairs done involving the engine cooling system. Sometimes if the cooling system is drained and allowed to dry out for a day or so sludge can partially block the radiator. This lowers the radiators efficiency so that any increase in engine load results in a rise in temperature. When the car is hot try feeling the radiator core with your hand (watch those fans!) to see if there are any cold areas where coolant isn't flowing.

 

[compress ignite]

Over heat?

Start engine , warm up...at idle in park , turn on Air Con... do the two smaller
electrically powered fans in front of the radiator come on?
There are two pressure switches (one Low, one High) in/on the refrigerant
lines.The low pressure one does not allow the compressor to engage if
there is not enough refrigerant.The high pressure one turns on the electric
fans.If it's bad or disconnected you will not get the electric fans running.
And then you would get an overheat situation at idle with the AC on.

 

[syeddanial]

hi panason1c

I'm no expert on air-con but i do believe that 'overcharging' (too much gas/oil) the system will cause the compressor to excessively load the engine. When you turn on the air-con with the engine at tickover does the engine slow down noticably?

Well, i just did an oil change and what happens is when the air con is turned off, the engine rpm was above 1k and goes back down to 700k. When the air con is on, it does the same and goes back down to 700k...this is when the engine is idile.

The temp will go above the 95 mark, somwhere around 2/5 of the distance between the bar to the 120 bar and thats when the second fan speed clicks in..and when this happens, it will go down below the bar on a level. Sometimes it will go down to a level just above 80. This applies when both the air con on and off?

The funny thing is when the air con is off, then the rpm depreciate from low to high and back to low...

 

[syeddanial]

Start engine , warm up...at idle in park , turn on Air Con... do the two smaller
electrically powered fans in front of the radiator come on?
There are two pressure switches (one Low, one High) in/on the refrigerant
lines.The low pressure one does not allow the compressor to engage if
there is not enough refrigerant.The high pressure one turns on the electric
fans.If it's bad or disconnected you will not get the electric fans running.
And then you would get an overheat situation at idle with the AC on.

Hi Compress Ignite,

The 2 small fans are working. The fans are working once there is pressure. It will also work when the air con is off. Though it will not work when i start the car in the morning . i guess what you mentioned about the pressure is correct. There are 2 speed. The low speed acts once the engine becomes hot and then when it reaches above the 90 bar, the 2 small fan and the large fan goes 2 times faster. My mechanic said that if i pulled the connecting wire for the temp which reads the engine temp, it will activates the fan on the high speed.