A quick question!!! Is the engine temperature too high that will shut down the whole A/C system automatically??? My 87 190E seems A/C system shut down automatically when the temp gauge over 110 degree. Also, when traffic jam, the temp gauge level almost hit at the top, but no overheat light on!!! After the car moving, the temp will down to 85 to 90!!! I changed coolant, waterpump, radiator already!!! Do other members 190E are the same or just my car like that???

I'm not aware that there is an A/C shutdown function at high engine temperature.

At idle and stop and go driving in hot weather, expect the temperature to go up to as high as 105C. A this point the dual electric fans will engage at high speed and they will rapidly bring the temperature down to about 100C where they disengage. This cycle will continue until you get up to steady speed such as freeway cruising where the temperature should run about 90 in hot weather.

Even though the mechanically driven fan' thermo-viscous clutch tightens at bout 100C this fan does not provide much air flow at idle speed, but the electrics at high speed are like a hurricane, and if the temperature doesn't drop rapidly, the radiator is probably clogged and needs to be replaced. Same situation on the highway. If it runs consistently over 90 at freeway cruise the radiator is probably clogged with deposits, which signficantly reduces its heat tranfer rate.

You can test the fan operation by letting the car idle in hot weather. At about 100 rev the engine to about 2000. You should hear "fan roar" and feel greatly increased flow realtive to flow at below 100. Let the engine continue to idle and check for engagement of the dual electric fans at about 105C. Do this test first with the A/C off. The do it with the A/C on and Min on the temperature dial and the windows open. The electrics should engage periodically at low speed based on the A/C pressure swtch. This will help cool the engine, but the coolant temp will probably evenatually creep up to 105, where the electrics should engage at high speed. If the A/C shuts down, check the freon level. It may be low.

The gage has a hash mark at 100 and 120 is the top. So what it the highest reading you are seeing - relative position of the needle to the above two hash marks?

Duke

Jeff

Is your 190e a 2.3?

Haasman

__________________
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)

yes, it is 190E 2.3L 8V.

Jeff

When I had a 2.3 I found that using a "water wetter" product worked well as advertised. It lowered temps about 10-15 degrees.

Haasman

__________________
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)

Some claim Water Wetter reduces coolant temps, most say it does nothing to coolant temps. The anecdotal evidence is inconclusive, and there is no science to support lower temperatures with a simple additive.

I am always concerned about adding aftermarket products to any OE recommended fluid as one never knows if there are incompatibilities.

The first thing that one needs to understand are the basic design algorithms of the fans and the normal temperatures this yields under various driving and ambient temperature conditions.

Another consideration is that early 2.3s had and electro-magnetic engine driven fan clutch, not a thermo-viscous clutch. The former engages at about 100C and locks the fan to the hub, so it will always turn at pulley speed and not slip at higher revs like the thermo viscous clutch when it is "engaged".

The 2.3s with electromagnetic fan clutch also had a single auxillary electric fan that engages at 105C or under the command of the A/C pressure switch. I'm not sure if the later 2.3s continued with the electromagnetic clutch or transitioned to a thermo-viscous drive. The latter is easily recognizable by it finned hub. The former engages with an audible "click" when it is energized.

Duke

Your fan or relay is dead -- aux fan should run at slow speed with AC on. You also have a defective electric fan clutch or relay as the engine temp should never get above 105C this time of year, even it traffic. You should also check the resistor for the slow speed on the fan, a broken or corroded wire will prevent it running at slow speed. Should still kick on at 110C , though.

The AC will kick off when the head pressure gets too high, as it is when sitting it traffic with no fans running. This is to prevent the high pressure hoses from blowing up.

Last, check the radiator cap. If it's old, replace it, else it will allow the engine to boil and greatly reduce cooling.

I suspect a bad fan clutch, myself.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Peter:

I replaced radiator cap, A/C relay, Aux Fan switch last year. I will go ahead to replace fan clutch and see what happened. I saw the Aux fan working last week, i will use directly power to it and test it working or not. Thanks

Just following up!! Replaced a brand new fan clutch and the temp seems go down to 80 to 85 degree on city driving. Sometimes around 100 degree (should be under 100) in slow traffic!

Normal behavior. The fan clutch is engaged at 100 or 105C and runs until 85 C, so the temp will oscillate between those two values.

Make sure the aux fan runs properly for good AC operation, and the engine fan will be inadequate in slow traffic.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!