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Discussion Starter #1
hi everyone and Merry Christmas.

i have posted this problem on another forum and we have not come up with a solution so see how you all see it.


i have an NF Fairlane 6cyl on gas. i had a problem start about 2 months ago when as i was driving a bit hard or going up hill or reving the car the temp would slowly rise until the temp got to 3/4 on the gauge( the R on NORMAL) and at that point the A/C would shut off (this is caused by the cut off on the comp) the fans would go to high and it would cool back too 1/4 ( L ) and after about ten minutes the A/C would come back and off we went again.

as i own a car yard i have plenty of workshops so i sent it to one and they said it was a blocked radiator. what i am about to list is what we have now done or replaced on the car up until yeasterday.

head gasket replaced and reco head, thermostat(various dec), water pump, new radiator, ECU, all hoses, temp sensor, whole system flushed and a new radiator cap. we also had the fans wired up to run on med/high when the A/C is on and high when the car reaches a preset point via a davies graig controller. all of this mad eno difference at all!!!! :wnc:

we then took the trans oil cooler off and cleaned the condenser as some times a small leak from the oil cooler will block it up. this worked a bit and the temp sat lower on the gauge(just below the L) but still when you rev it too high or drive hard or a hill it climbs. so some one suggested i let some A/C gas out. we did this and the car stayed at 1/4 longer but eventually climbed but this was the first time we had any real gain. so we took it to a A/C shop and he said the head pressures were very high and this was because the car was getting hot.

so we are now at the point where the car actually runs cold at idle and takes a while to get warm thats how good the cooling is working! what we found today is if you hold your hand behind the thermo's at idle you feel some heat being sucked off the radiator and condenser but when you turn off ths A/C it drops, ok thats normal, but when you hold the revs at 2-3000 with the A/C off there is afair bit more heat as the engine is working harder and thats right but the moment you turn on the A/C the heat goes to a point where you cannot hold your hand there i mean it gets really hot and i dont think thats right and when you look at it thats been the problem all along--- fine at idle/low speeds cool days but on hot days/acceleration/hills or hard driving temp goes up.

answers please? :bsr: could the A/C OVERHEAT THE CAR? when it does get hot if i slow down or stop the fans cool it down very quickly :AAHHH:
 

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300+rwkw DC LTD Member
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1,622 Posts
By the sounds of it you've replaced more than ya needed too.

Have you put an aftermarket temp gauge on it?

Does it get this hot on Petrol?

Is the LPG tuned?

It also sounds like the thermostat is buggered!
 

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known as tibbo
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by the sounds of it ..seeming how the cooling system is almost new..i'd put my money on the A/C compressor clutch bearing being very stiff or completely rooted (but not at all noisey) . Whats the underside of the fanbelt look like? If the A/c compressor requires more force to rotate it maybe it is also slowing down the water pump drive too?
 

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EB wagon
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Ummm... this happens on my car.... I thought it was normal??? With the A/C on, my temp needle wonders up to the top of the normal block and stays between there and half way. With no A/C it sits on spot on half. Sometimes it wanders up a tad until the thermostat opens more but then comes back down. It does say "NORMAL" and is within this range so i assumed this is OK!

Brent
 

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Wow thats very high, my ED sits on 'o' in normal for me and with A/C on with a bit of hard accel ion traffic in freaky hot day it wil get to 1/2 but otherwise will only move to 'r'.
 

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known as tibbo
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2,033 Posts
ahh the more i think about it are you 100% postive the second thermo is engaging with the A/C compressor... not to be a smart ass but incase you don't know and want to check BOTH fans are spinning get a drinking straw or a long cable tie and actually poke it inside the shroud ...
 

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Discussion Starter #7
thermostat has been checked and replced twice just in case we also ran it without one-- same. both fans are working for sure.we thought about the compressor but the problem there is if it was holding the motor back the temp would not drop when you go to idle or drive gentley as it is still pumping. and if the pump was sticking it would over heat far quicker and shut itself off
 

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Lord of the RC
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Wow your cars sti very high

Mine doesnt even get past the L with a/c on flat out ( a/c max + fann on boost ) and a really hot trip

Would agree with something on the a/c is causing it to get that hot
 

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Hmm... this won't really help the original question [sorry!] but one thing i've noticed is that some people are confusing the dash readings. i.e. if your temp guage runs clockwise (from left pointing to top) then N is quite cool ... but if it runs anticlockwise (as my EF, from right pointing to top), then N is far too hot. When people speak of temperatures, can we speak in say, percentages, or at least specify which dash you have or something, etc

Cheers!

jasonk
 

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When you had the head gasket changed did the pistons & head look ok, no sign of detonation or running lean? Is the overheating problem only occuring when you use let's say gas or petrol or both? Does the car ping & does the power drop off? Check your spark plugs for any signs of detonation and to see if the motor is running rich or lean. Also see if the spark plugs you have are correct heat range (gas sparkplugs are 1 heat range colder then petrol because gas runs hotter) & check the gaps on them while you are at it. Also check the drive belt & pulleys for signs of sliping & check the temperature sending unit to see if it's inoperative.

The only other thing that I can suggest is to get the fuel mixture & timing checked.

When the A/C system comes on it puts more load on the motor and if your fuel mixture is wrong to begin with it makes it even harder for the motor to operate properly (eg lean). If the power is poor the knock sensor could be retarding the timing too much cousing the power to drop off and engine to overheat.

U said that the radiator was flushed. Did you check the block for any major rust, scale or any other foreign material? If the car was running without coolant for a long time it could have developed a lot of rust preventing the coolant too cool it properly?
 

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Discussion Starter #12
engine is running fine no power loss (when it gets hot a little) all sensors have been replaced and then checked. radiator was new and block was flushed. workshop gave everything a check over when head was off. we thought about the cars ignigtion being retarded but again it would show up constantly. the plugs are the correct ones for gas and it has the problem on gas and petrol.

we are starting to think nore and more its the a/c. yeaterday we did the hand heat test on the fans and when the engine is at idle or up to 3,500rpm you can feel a reasonable amount of heat being pulled through the fans more on the left than the right which is correct as the left is the hotter side but the moment you turn the a/c on the heat from behind both the fans is so high you cant hold your hand there for more than a few seconds. the moment you turn the a/c off it holds the heat for about a minute then it slowly goes back to a point where ther is warm to hot air pulling through
 

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Does the A/C blow warm air and does it cool properly? Have you tryed running a different A/C unit to be 100% sure that it is the A/C that's cousing the problem?

Do these test to see if your A/C could be faulty

Try and test the Magnetic Clutch to see if it engages properly, See if the Compressor rotates properly, Check the temperature control resistor, Check to see if the condenser & receiver are clogged or if the expansion valve, A/C Amplifier, water valve set, pressure switch are faulty, check to see if there is excessive oil in the compressor system.
 

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Discussion Starter #14
a/c is icy cold and has been checked by 2 people only thing to show up was high head pressures whice was put down to not enough cooling air over the condenser
 
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