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Discussion Starter · #1 ·
I've been working on a 03 LX with a 2.3L engine. This car was my uncle's who passed away last year and his son did not want it, so it was left to me. After I finally got it to pass Cal SMOG and registered (big ordeal). I had the A/C system recharged. A/C blows cold now it's starting to get hot in SoCal. On a normal warm day (80F) the Coolant temp is fine, around the middle of the gauge. I've even checked it on my scan tool to be around 220F. Today being a hotter day 90F+, it started to overheat to almost the RED, I did not have my scan too with me but it alarmed me. I quickly pulled over and checked the engine bay. The reservoir was still full and no signs of leaks. I let it rest a few minutes with the hood open while I went to the store to get a drink. When I came back and started the car the temp was back to normal. I let it idle for a few minutes to see if would start to get above normal again. It did not, so I drove straight home. The temp was normal, but as soon as I turned on the A/C it started climbing again. So I was playing with the fan speed settings and noticed the temp gauge would climb up slightly as I increased the fan speed. Not sure how's it's related but I thought to mention it. It was cooler the previous week after I got the A/C recharged, so I did use the A/C as much and used a low medium fan speed (2).

What could be causing the coolant temp to go up when I turn on the A/C? Low voltage from the battery?

I'm about the flush the cooling system, since it been sitting for about 8 years. But I've been using the car intermittently while trying to fix some SMOG related issues over a 5 month period. I did not get the A/C recharged until the SMOG issues were cleared. What is the recommended coolant for this Focus? OAT or HOAT? I'll probably just drain what I can and fill with distilled water just in case I need to replace the water pump or thermostat.

Thanks in Advance for any suggestions.
 

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The engine cooling fans are supposed to speed up when a/c compressor loads go up. Not doing so will overheat as you turn the a/c up as the evaporator gives away more heat to condenser at greater blower fan speed calling for more engine cooling. Fans go on high past about 270 psi highside of the compressor. If not doing it you will begin to climb in engine temp.
 

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So I was playing with the fan speed settings and noticed the temp gauge would climb up slightly as I increased the fan speed. Not sure how's it's related but I thought to mention it.
The fan speeds you are talking about are the blower fan in the passenger compartment that blows the heated or cooled air at you. The fans AMC is talking about are the two engine cooling fans near the radiator in the engine compartment.

You could have an issue related to the coolant circulation system - water pump, thermostat, radiator, etc. Or you could have an issue related to the engine cooling fans. It is critical that the engine cooling fans are operating correctly.

On your 2003 2.3L Ford used a setup where the two engine cooling fans are controlled by the PCM based in input from the cylinder head temp sensor (CHTS) or engine coolant temp sensor (ECT).

Does you vehicle have the dual cooling fan setup?

Does your engine compartment fuse box have one or multiple cooling fan relays?

Paul
 

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I would test the fans are coming on. Turn the temp to hot and blast the fan to 4. The radiator fans should be turning on at this time. If not, that could be your problem. Coolant wise, i would use G05.

Sent from my moto g(7) power using Tapatalk
 

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Discussion Starter · #5 ·
The fan speeds you are talking about are the blower fan in the passenger compartment that blows the heated or cooled air at you. The fans AMC is talking about are the two engine cooling fans near the radiator in the engine compartment.

You could have an issue related to the coolant circulation system - water pump, thermostat, radiator, etc. Or you could have an issue related to the engine cooling fans. It is critical that the engine cooling fans are operating correctly.

On your 2003 2.3L Ford used a setup where the two engine cooling fans are controlled by the PCM based in input from the cylinder head temp sensor (CHTS) or engine coolant temp sensor (ECT).

Does you vehicle have the dual cooling fan setup?

Does your engine compartment fuse box have one or multiple cooling fan relays?

Paul
I have two engine cooling fans and they both seem to work. When I first got the car, back in Dec., I took it for a drive and when I parked it the Radiator cooling fans were still going after I turned off the engine. After that the battery had drained and I needed a jump start. I ended up replacing the battery and it never happened again after that.

I don't remember but I think I have two relays. One I know for sure is the A/C relay.
 

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I have two engine cooling fans and they both seem to work. When I first got the car, back in Dec., I took it for a drive and when I parked it the Radiator cooling fans were still going after I turned off the engine. After that the battery had drained and I needed a jump start. I ended up replacing the battery and it never happened again after that.

I don't remember but I think I have two relays. One I know for sure is the A/C relay.
You probably have a two speed fan setup - most Focus do - but Im not that familiar with the 03/04 2.3L PZEV setup. Unless you fans work in low and high speeds (if you have the two speed setup) your engine cooling will not be adequate. Can you post a pic of your engine compartment fuse box?

Paul
 

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Discussion Starter · #7 ·
The engine cooling fans are supposed to speed up when a/c compressor loads go up. Not doing so will overheat as you turn the a/c up as the evaporator gives away more heat to condenser at greater blower fan speed calling for more engine cooling. Fans go on high past about 270 psi highside of the compressor. If not doing it you will begin to climb in engine temp.
I was talking about the blower fan inside the cabin. As far as I know the radiator cooling fans are working. The A/C system was vacuumed then recharged to the correct specs on a Snap-On A/C unit. It was tested for leaks before the Freon was added.
 

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Discussion Starter · #8 ·
You probably have a two speed fan setup - most Focus do - but Im not that familiar with the 03/04 2.3L PZEV setup. Unless you fans work in low and high speeds (if you have the two speed setup) your engine cooling will not be adequate. Can you post a pic of your engine compartment fuse box?

Paul
I'll take a picture tomorrow, it's not at my house.
 

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'Turn the temp to hot and blast the fan to 4. The radiator fans should be turning on at this time.'

That is incorrect, it may well turn the radiator fans OFF. Opening the heater duct allows the heater core to cool engine too and it then lowers the engine heat to cut fans back. Poster is mixing up the two fan sets.

If you do not have the bumpup in speed to high with a/c on BOTH fans it may well overheat. Don't know about that one but earlier ones even bump up based on a/c pressure alone, it is NOT tied to engine temp at certain times. Both rad fans work as a set both are on low or high, not just one.
 

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Discussion Starter · #10 ·
You probably have a two speed fan setup - most Focus do - but Im not that familiar with the 03/04 2.3L PZEV setup. Unless you fans work in low and high speeds (if you have the two speed setup) your engine cooling will not be adequate. Can you post a pic of your engine compartment fuse box?

Paul
310132
 

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The large (tall) red relay (upper center of photo) is the high speed fan relay. This relay also has a built-in circuit that allows the fan to run in high speed for some time after the ignition is shut off.

The gray relay (lower right of photo) is the low speed fan relay.

Both relays can be removed (carefully) and bypassed (jumpered) to test the downstream fan circuits and fans in each respective speed.

Let me know if you want to do these tests and I can tell you which contacts to jumper.

Paul
 

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Discussion Starter · #12 ·
The large (tall) red relay (upper center of photo) is the high speed fan relay. This relay also has a built-in circuit that allows the fan to run in high speed for some time after the ignition is shut off.

The gray relay (lower right of photo) is the low speed fan relay.

Both relays can be removed (carefully) and bypassed (jumpered) to test the downstream fan circuits and fans in each respective speed.

Let me know if you want to do these tests and I can tell you which contacts to jumper.

Paul
Thanks, Paul!

I drove it today to get an oil change. It was not as hot as yesterday and I had my scan tool to look at the live data, specifically the ECT. I was not in stop and go traffic like yesterday and I had the A/C on with the blower fan on 2. It was pretty steady at 206F but peaked to 220F at a stop.

I did not get a chance to flush the coolant, but I did buy the distilled water I'm planning on using. The coolant color is a dark green like, so I don't know if it's a mix of yellow Prestone and Euro Blue.
 

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I'm about the flush the cooling system
Water flushing will help but won't cure 18 years of rust and scale. I've used Thermocure but there's also Irontite Thoro-Flush. Be advised, some people claim leaks after use. Never happened to me yet though.

If you try Thermocure, use only half the bottle per treatment, in a 6 quart system. Shake well.
 

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Other common problems are debris built up between the A/C condenser and the radiator, and the fins of the A/C condenser and radiator get plugged with trash too.

Something to check while you’re under the hood.
 

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Discussion Starter · #15 ·
Other common problems are debris built up between the A/C condenser and the radiator, and the fins of the A/C condenser and radiator get plugged with trash too.

Something to check while you’re under the hood.
Thanks Dan! I was thinking that too not much grill exposure for air flow. I was had to remove the cover to get to the top of the radiator and condenser.
 

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Discussion Starter · #16 ·
One week Update: After flushing the cooling system and filling with distilled water it has not overheated even when it was almost 90F today. I drove in stop and go traffic and it did not even go past the center. I was also monitoring with my OBDII reader and the highest it went to was 216F but quickly dropped when moving. The coolant was still slightly green so I'll run it a little more before draining and refilling with the G05 and distilled water.
 
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