What Is the fix for Engine hot/AC off?

Hi Karan,

The normal reason for this light to come on is to tell you that the car has disabled the air conditioning compressor because it's seeing an engine temperature that's too high.

Since that part should be pretty obvious, I assume you're seeing this light when the car is not overheated and are thus confused by it, is that right?

As it turns out, you're not the only one this has happened to. Several people have reported the same problem and have gotten a few different answers. In general, the first thing you want to do is to scan the engine computer for any Diagnostic Trouble Codes (DTC's) that are present in the system. If found, they should point you in the direction of where the error is coming from. Here in the US, most auto parts stores will scan your car for codes for free; just stop in and ask.

According to Gregg Lathem, ASE Certified Master Technician over at JustAnswer.com, here's what that light means.

Engine Hot AC off means the PCM "thinks" the engine is overheating, so it disables the A/C compressor.

If the engine is not actually overheating, the problem could be a faulty coolant temp sensor, shorted/open wiring or failed PCM.

Here's the diagnostic procedure he recommends for troubleshooting this problem.

The first step in diagnosing this fault would be to scan for any stored Diagnostic Trouble Codes (DTC's) in the Powertrain Control Module (PCM).

If no codes are stored, diagnosis will require a fully compatible scan tool that will allow you to view actual PCM data information.

This error (Engine Hot A/C Off) is triggered when the PCM sees more than 5 deg. (F) between the Engine Coolant Temperature Sensor and the intake air temperature sensor which is incorporated in the Mass Air Flow Sensor (MAF).

1. From a cold start, monitor the coolant temperature and the intake air temperature sensors, they should be within 5 degrees of each other.

2. If either is off, verify the ground is good and the 5 volts to the sensor is good. (See attached documents)

3. Replace the sensor that reads incorrectly and retest.

So I would suggest getting the codes scanned as the first step. If there are trouble codes present, come back here and add them to your question and we can go from there trying to get you fixed up.

Otherwise, if you don't have access to the fancy scan tools needed, I would probably check the connector going to the coolant temperature sensor and if there's nothing obviously wrong with it, then replace the sensor and see if that fixes the problem. If it doesn't, then the other suggestion would be to replace the Mass Air Flow (MAF) sensor. I'd check around for prices on those, though; I've seen some of them cost a lot of money and others are reasonably affordable.

Good luck with your repair, and let us know what you find!