High engine temp, A/C not cold, Aux fan prob, erratic idle
06-01-2005, 08:05 AM
#1
Member
Thread Starter
Join Date: May 2003
Posts: 159
Likes: 0
Received 0 Likes
on
0 Posts
High engine temp, A/C not cold, Aux fan prob, erratic idle
My 93 400E has been seeing higher engine temps than normal. Ive had the car for about 10yrs and temp stays at or below 80 degrees 98% of the time, may (rarely) climb up to 85 to 90 when stuck in really bad traffic or when driving up long ascent. Nowadays, normal driving would have the engine temp at about 90 to 95, and would go up to about 100 when in traffic. Two of my friends have 500E's and normal temp for them is also about 80 degrees, so Im pretty sure 80 degrees should be the correct normal temp.
I started experiencing these higher than usual temps about a month ago after I got the car back from the shop. It was in the shop because the A/C would cool intermittently. The cold air from the A/C would come and go while driving, sometimes turning the A/C (or car) off and on again will bring back the cold air. Sometimes, no matter what I do I cant get the A/C to work again. Ive popped the hood and noticed that the A/C compressor clutch is not engaged whenever the A/C stop blowing cold air. I have noticed the A/C malfunctions less at night.
Some other notes:
1.) I tried unplugging the connector from the blue temp sensor on top of the engine, this causes the aux fans to be at high speed all the time. Temp stays at about 70 to 75 degrees all the time, but the A/C will not cool at all when I do this. And Im sure the aux fan is not meant to be on at high speed all the time.
2.) I discovered the shop had unplugged the two connectors from the green plastic pressure switch installed on the side of the A/C dryer tank from the two female connectors from the wiring harness. They then spliced together the two female connectors of the wiring harness. Now the aux fans are permanently on at low speed, engine temp stayed at about 80 degrees, A/C would now work, but still intermittently.
However, based on what I remember, and based on what my friends with 500E's tell me, its not normal for the aux fans to on at low speed permanently. And Im sure there must be a reason why MB hooked up those wires to the green pressure sensor so I dont want to just simply unplug them.
3.) I reconnected the female connectors of the wiring harness to the male connectors of the green plastic pressure sensor, now the aux fans are off and not permanently running at low speed. Engine temp high again at the 90 to 100 range, A/C still not working properly, plus engine idle now fluctuates by about 50 to 100 rpm. Idle returns to normal when I disconnect the female connectors from the green plastic pressure switch and splice them together.
4.) Visco fan is new, water pump is new, radiator is in ok shape, coolant is new. Not sure about thermostat.
Anyone here can help? This is driving me crazy.
I started experiencing these higher than usual temps about a month ago after I got the car back from the shop. It was in the shop because the A/C would cool intermittently. The cold air from the A/C would come and go while driving, sometimes turning the A/C (or car) off and on again will bring back the cold air. Sometimes, no matter what I do I cant get the A/C to work again. Ive popped the hood and noticed that the A/C compressor clutch is not engaged whenever the A/C stop blowing cold air. I have noticed the A/C malfunctions less at night.
Some other notes:
1.) I tried unplugging the connector from the blue temp sensor on top of the engine, this causes the aux fans to be at high speed all the time. Temp stays at about 70 to 75 degrees all the time, but the A/C will not cool at all when I do this. And Im sure the aux fan is not meant to be on at high speed all the time.
2.) I discovered the shop had unplugged the two connectors from the green plastic pressure switch installed on the side of the A/C dryer tank from the two female connectors from the wiring harness. They then spliced together the two female connectors of the wiring harness. Now the aux fans are permanently on at low speed, engine temp stayed at about 80 degrees, A/C would now work, but still intermittently.
However, based on what I remember, and based on what my friends with 500E's tell me, its not normal for the aux fans to on at low speed permanently. And Im sure there must be a reason why MB hooked up those wires to the green pressure sensor so I dont want to just simply unplug them.
3.) I reconnected the female connectors of the wiring harness to the male connectors of the green plastic pressure sensor, now the aux fans are off and not permanently running at low speed. Engine temp high again at the 90 to 100 range, A/C still not working properly, plus engine idle now fluctuates by about 50 to 100 rpm. Idle returns to normal when I disconnect the female connectors from the green plastic pressure switch and splice them together.
4.) Visco fan is new, water pump is new, radiator is in ok shape, coolant is new. Not sure about thermostat.
Anyone here can help? This is driving me crazy.
Last edited by amgmercedes; 06-02-2005 at 01:11 AM.
06-01-2005, 11:54 PM
#2
MBWorld Fanatic!
Join Date: Apr 2005
Posts: 1,594
Likes: 0
Received 0 Likes
on
0 Posts
Mercedes-Benz w124
hmm went on a drive this afternoon with my mom and this was annoying me. the ac was cold enough. not ice cold but doable. i set the switch for the white fan ( the top one ) so that it could get cold in there since today was a really hot day. so i turn it on and it takes a while for it to kick in.. about a minute or so. by that time the car has been fully warmed up to 82 degress Celsius. then it works fine for a couple of minutes ( 7ish ) then it just stops... i seemed to think that it would turn off when i stopped the car. i was in the streets and there were many red lights. then on my way back i was cruising down the street going about 45 and then it would just stop... then 30 seconds later, it would start up again..very annoying. i would like to get this fixed... this is going to be a hot summer and i don't want to suffer. ideas of cost???
06-02-2005, 02:42 AM
#3
Senior Member
Join Date: Jun 2003
Location: Salem, OR
Posts: 302
Likes: 0
Received 1 Like
on
1 Post
08 Lexus GS350 AWD. 08 Lexus RX350 AWD - wife's. 94 MBZ E320 - still have it.
It could be a climate controle unit malfunctioning. (the thing with all the AC/heater knobs and push-buttons). It is a VERY common problem on the 124 Mercedes.
