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Overheating Problem 2003 Mach 1

3629 Views 5 Replies 4 Participants Last post by  Kevin88
2003 Mach 1 with Roughly 150,000 miles.

I was driving around town, had the Max A/C ON. Nothing out of the ordinary was happening, no strange smells that I remember anyways, gauges were not reading anything irregular.

I stop for a quick bite at sonic. While I'm there, the vents start blowing hot air, so I turn off the A/C, get my food and start to leave.

Then, I decide I might as well try the A/C again (I figured it was just low on freon) it's hot air still. So I roll the windows down as I pull out into traffic (I don't remember if I turned the A/C off at this point or not) and it starts billowing steam out of the hood (it was pushing past the radiator cap).

I'm turning into a major intersection so my only thought was to get to another safe stopping point. I don't remember exactly, but I THINK I saw the Voltage Meter pegged on the high side.

I then parked it quickly, caught a ride home grabbed my truck and trailer and haven't really driven it since.

First I put a new radiator cap on it and filled it back up with water.

Next I noticed that the fan relay/capacitor/resistor looking thing (the one that mounts in the shroud with 3 prongs on it) was not in the shroud, but instead dangling freely. I know that this has to do with the way the fan switches from Low Speed to High Speed, so I thought I had just found my problem. Even tested the fan motor by using some wire to run from the battery to the fan pigtail and another to the ground and the High speed worked. However...

I ran a jumper wire (bypass resistor), so that anytime the fan was on it was on High (no resistor to limit the electricity for Low, I may be wrong somewhere with this but it made sense to me).

3rd step. I turn on the car, Max A/C ON. Assuming I did the jumper wire correctly the fan should be on when the A/C is On (Correct?).

Well the fan didn't come on.

At this point I feel like it must be the fan. I should just buy an entire assembly and it might fix the problem... But I don't have money to throw at it if this isn't the problem.. And it didn't work with the jumper wire, so I decide to just let it sit for a few days while I try to figure something out.

Now today.. I go fire it up and just run through a few troubleshooting steps again. I turn the max a/c on and it doesn't even blow cold air even for a few seconds (initially it would be cold then become hot air).

So I grab a can of freon and my gauge and pop the cap off (more pressure under the cap than I realized..) and had trouble getting the gauge on it.
But when I did, the gauge jumped into the red REAL FAST. So I pull the gauge off and quickly turn the a/c completely off...

I've been searching and searching (for like a couple hours anyways) through tech threads with this exact situation and haven't found any.

My question...
Is it possible that an A/C compressor being seized would show my freon pressure to spike, or is that because the cooling fan is not turning?

Which would cause the first problem?
Cooling fan failure causing A/C to show such a high pressure? or A/C Compressor failure causing the fan resistor to burn up, the causing the overheating?

Or my main suspect before today's experience with the freon...

The Fan Resistor fell out of the housing, grounded out against something (causing the voltage spike that I think I maybe saw?), which then caused the Cooling Fan to fail, resulting in the overheating because I was sitting still at sonic with no fan on at that point (and it was the first time I felt the hot air with the a/c on). And today the fan wasn't turning when I checked the Freon level, could that give me a high pressure reading?
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it the resistor shorted you likely have blown a fuse.
no power no fan. no fan no cool.
Check for voltage first.
never add Freon without checking pressures. if the pressures are low you need to find the leak first then fix it. then replace the Freon.
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