I have been through 3 condensor fans in the 18 months I have owned the vehicle, trying to identify what the cause is. Figured I was running hotter then normal because when I don't run the A/C, my condensor fan turns on about 10-15 min after i start the truck. No matter what the ambient temp is it runs constantly while I am driving. I decided to put a temp gauge on the car to start and see what i was running at and at what temp the fan was coming on.

Put one on last week, here is what I see

The fan seems to turn on at about 160 consistently
Around town temp doesn't go above 185-190 (25-45mph)
At highway speeds (70-75mph) its at about 170-175
Idle (20 min) it will get to about 200 and then thermostat opens (i think) and it goes down to about 190-195

Are these temps normal, I am going to hook up a reader tomorrow to ensure that my guage is accurate but thought they they seemed low. Does anyone know what temp the condesor fan comes on at and why my fan runs constantly (outside of A/C being on)? Is there another issue I should be looking at thats causing it?

Any help appreciated and apologies for the wordiness...

 

Sounds like maybe a bad temp sensor telling the fan to come on at way too low temps. I'm not sure, however exactly where this sensor is located. RAVE manual should tell you.
Good Luck!

 

That sensor is on the inlet manifold. Many stange gremlins are defeated on a D2 and newer by putting in a new battery, and cleaning all battery cables and large cables in the underhood fuse box. Here is info from the RAVE about all this:

DESCRIPTION

General

The cooling fan is located on brackets forward of the radiator. The fan motor is operated by
a cooling fan relay controlled by the Engine Control Module (ECM). The main relay supplies
a feed to the coil of the cooling fan relay. A permanent feed is supplied to the coils of the
main and cooling fan relays located in the engine compartment fusebox. On V8 models a
coolant temperature sensor is located in the inlet manifold, on Td5 models the sensor is
located in the outlet housing.
The ECM controls the operation of the main and cooling fan relays. At a preset temperature
the ECM receives an input from a coolant temperature sensor above the values stored in
the ECM. The ECM logic enables the earth path for the coil of the cooling fan relay. The fan
motor then gets a feed from the closed contacts of the cooling fan relay.
When the engine temperature falls, the sensor gives an input below the values stored in the
ECM. When the input from the coolant temperature sensor is low, the ECM interrupts the
earth path to the coil of the cooling fan relay. The contacts of the cooling fan relay open, this
action breaks the feed to the cooling fan motor, and the motor stops. The cycle will start
again when the engine coolant temperature rises and the sensor sends a high input to the
ECM.
The ECM has an engine off function, when the ignition is turned off the ECM logic goes into
a watchdog routine and monitors the coolant temperature for approximately seven to ten
seconds. If the coolant temperature is still high, over 100 degrees C (212 degrees F) V8, 110
degrees C (230 degrees F) Td5, the ECM logic can control the operation of the fan motor.
On V8 engines the ECM will only enable the fan if the inlet air temperature is over 60 degrees
C (140 degrees F). The ECM will allow the fan to run for a maximum of ten minutes, however
the ECM continues to monitor the coolant temperature. The ECM logic will stop the fan if the
coolant temperature is below the acceptable values stored in the ECM. To prevent a flat
battery, the fan will be stopped (regardless of coolant temperature) if the battery voltage falls

to 12 V.

 

Disc oh no...battery is new last year and terminals, cables etc are all clean. Voltage is good...i would think that a temp sensor would either be bad or good but i will check connections for corrosion etc...

SBUzz...For the RAVE download, I had read through that but it doesn't give you a temp that it comes on at, just says a "predetermined temp" didn't know if anyone had any idea what the temp was it was supposed to come on when the engine is on.

as always thanks for the help

 

Are you installing new, used or after market fans?
The t/sat starts to open at 180, fully open at around 192 and the fan will usually come on just under 200 degrees of stop and go driving and or with the a/c on.
Your numbers are all off/innacurate.

 

Not sure about this particular sensor but I had a Vokswagen that had Bosch sensors in it and the trigger temp. was stamped right on the metal part of the sensor itself.
If you are getting the temp from a scanner plugged into the OBD port you will get totally wrong temps if that sensor is bad. I just changed one on a Chevy S10 a couple weeks ago because it was throwing codes and when I hooked it up to the OBD scanner the temp. was 34 degrees when I first hooked it up and then jumped to 89, then 103, back down to 31, etc. all in a matter of seconds. So it had no idea what the temp was and the fuel system loop would not close. It's like running it with the choke on constantly. Bad for fuel milage and everything else for that matter.

 

So finally I hooked a scanner up to the OBDII port and the engine temps at idle with hood open were 220-225. When i give it some RPMS and the fan clutch kicks in it goes to about 210-215 but once its idling again temp goes back up.

I got a infared gun and started checking hoses, radiator, block etc...the infared readings are in line with the Computer temp on the block, but all the hoses and radiator (where i could see it) were about 160-170 which is what my gauge was showing. Then I hit the hose that runs from the bottom of the radiator to the bottome of the thremostat with the gun...it reads 80 and is cool to touch.

Question: Is this a thermostat issue, a radiator issue or something else...assume that I would start by switching out the Thermostat (and switch to green). But before I do that wanted to get opinions that this was the right place to start.

 

First, you never test engine temp with the hood up and using an infra red scanner is not nearly as accurate as using a good scanner.
Re-read the temp number and get back to us.

 

The condenser fans will NOT come on no matter what unless the engine is hot enough, I think it is 160*F before they come on, this aids in engine warm up and reduces emissions. (a hot engine is more efficient and uses less fuel than a cold one)
It tells you in the owners manual about this.
Idle temps should be right around 200*F.
I believe there are 2 different temp sensors on the DII, one for the dash and one for the ECU, I do not know which one the a/c uses.
From the sounds of it your a/c thinks everything is fine so the condenser fans are on;y coming on when the engine temp reaches the pre-determined temp.

What was your reasoning for replacing the fans?

 

IMHO you might want to consider:

1. The temp going into the radiator and the temp going out are over 100 degrees apart, with truck warmed up. That is either a radiator much larger than a stock radiator ( and it is cooling a lot more ) or... the coolant flow through it is not as much as a clean radiator. A restricted radiator can't pass as much water as a clean one.

2. You could have a thermostat stuck open or partly open due to trash. If open, will make temp lower and unstable while underway, it does not "hold water" in the engine block to stay warmed up. While stopped, it does not "hold water" in the radiator long enough to cool off.

3. You have had this problem since purchase. Previous owner may have used stopz leekz radiator head gasket fix. That material will settle to lowest spots in cooling system, that being the radiator lower tubes (reduces cooling capacity) and the vertical mounted thermostat (changes operating points).

4. A partial blocked stat will exhibit on/off behaviour, as it does increase flow when it opens, it just does not close off all the way when it needs to.

5. Murphy's Law does not say just one thing will be wrong. You are able to have reasonable temps while driving, but they keep dropping as speed increases. Sounds like stuck open thermostat. You have overheat at idle, but fan clutch is "good" (we assume it is a little stiff even when hot, and does not allow free wheeling when spun by hand), and all fan blades haved cupped side facing engine block (all air should blow toward engine, both condenser fan and main fan). A reversed fan (blades mounted backward or wired backward) can cause overheat at idle. If you hold a wimpy plastic grocery bag at the grille, it should pull toward grille, not blow away from truck.

My PO reverse wired the fans, and they made it overheat at idle. Chased my tail on that for a while.

I went out and cranked up my D1, which is different, but similar sized block, and warmed up I am like 40 degrees apart inlet to outlet, and it is 50 degrees here, have a copper and brass radiator, recently rodded out, and a jumbo fan.

6. Using an IR thermometer is subject to a number of un-intentional errors. The beam width of the sensor is larger the further you are from something, it is not a laser dot. The laser pointer should be about the center of the detection cone. The closer you are to something the better the test. Air blowing on front of unit can impact readings. Reading outside of a rubber hose, side plastic tank of a radiator, and engine beside the coolant sensor will have different numbers. The D1 has two sensors , gauage and ECM; the D2 has a single sensor and the ECM calculates where the guage should be an sends a signal to it. Your data scanner is the best, as it reads raw data the ECM uses in a D1 or a D2.

Summary - you could have overheat due to fan wiring or blades mixed up during the multiple replacements; you have a stuck open thermostat due to PO use of stopz leekz, your radiator needs to be flushed for same reason. Fans are cheap to check. Flush radiator and new green or yellow coolant. New thermostat. Seems like if it was water pump you would have problems at speed on the highway.

You have not mentioned air in coolant (bubbles flowing thru heater under dash).

Guess you could use that IR thermometer to read temp of hoses below and above thermostat. Would seem like if stuck open they will be pretty close to each other. However, the stat does have four bypass holes that flow coolant all the time (if they are not blocked).

Note: D2 has a single coolant sensor, it drives multiple things. See attached from RAVE. And I guess that could also be defective. When unplugged it should make scanner read like -40 F. In many vehicles if this sensor is open, it makes engine rev higher at idle as ECU makes mixture richer believing truck is parked in the freezer.