Why does my gas gauge always show e and when I turn my headlights on it makes a noise

As Larry Ng states that is TOTALLY the wrong way to do it and TOTALLY the right way to wreck the system. If you can't do all this in this order, take it to a garage that does A/C!

Recharging a Vehicle Air Conditioner System.
Your vehicle AC not working as well as it did. You buy a couple of those refrigerant gas cans and a gauge from the Auto Shop, and think, I'll just add a couple of cans?

You can't fill an AC unit by guesswork. You also need the specified amount of compressor oil if you replace the compressor itself. This is how it's done. First you pressurize the system with inert nitrogen gas and check for leaks. Then you use a recovery pump to suck out all the gas into a recovery tanks until you have a strong vacuum. Then you put the gas bottle onto a subtractive scale. You Zero the scale (Tare) open the valves on the gauges and run the engine. As the gas leaves the scale, it add UP on the scale in Grams or Ounces. Always add as a gas, don't turn the tank upside down to add liquid gas as it will hydro-lock the compressor. The EXACT weight of gas is specified for that vehicle. It has to be right within a couple of grams. Not enough gas and it doesn't vaporize in the evaporator, (the part that turns liquid to gas in the dash area and creates cold. If there is too much gas, it damages the compressor as there is no room for the gas to vaporize, because the system is full of liquid gas on both the high side and the low side of the compressor.

Posted by ADMIN... on Jun 20, 2022

Take off the negative battery cable for 10 minutes. While waiting for that make sure you have all the ground straps connected that go to the battery cable end and to the engine.

Your alternator may be on it's last leg. Start the car and while the car is running, remove the negative cable from the battery. If the car dies, the alternator is no longer working. If you have a volt meter, put the meter on the battery positive and negative. You should read 13.8 - 14.2. If it doesn't show this, and reads under that, your alternator is not charging enough to keep your accessories going.

You need to check and make sure it not the hub bearing ( that the part where the belt rides around the a/c compr ) if all that look's good you'll need to hook some a/c gauges and get a reading, a good reading is about 25-40psi on the low side and about 150-225psi on the high side give or take 10psi, also look at gauges and look for the needles jumping, You need to remember that once a compressor start to make noise it's just a matter of time before it lock up. Unless it's only the hub bearing, that can be change out.

There is a pressure switch on the accumulator. The compressor cyles according to the low pressure reading at the accumulatror. If there is low refridgerent pressure the switch stays "OFF" and wont turn ther compressor on. Whan a system is low, there will be rapid cycling of the compressor, (on and off every few seconds). When the system is charged with the correct amount, the pressure is related to the temperature of the refridgerent. The compressors are common to leak. So it it doesnt leak, or make knocking noises, the compreesor MAY be good, but a pressure gauge will tell you if the compressor is good or bad. If you keep having to charge it, thats bad, and there is a leak. You will need to find and repair the leak, replace the drier (accumulator) , and recharge the system.

the most common cause would be the electric fuel pump inside the gas tank is defective and sticking.

The Sending Unit is Inside the Fuel Tank at the End of the Intake Line. You will have to Drop the Tank and Change it. Your Guage should be just fine after the Repair

It seems like a recharge may be in order. I'd try it for sure. Most recharge kits come with a pressure gauge that fits on the end of the coolant can and shows you how much refrigerant you have in the system.

This could be from a number of things. Do your electric cooling fans in front of the radiator always run, even when you first start the car with the A/C off? Does your temperature gauge function? Can you hear your A/C compressor click on or off when you turn it on/off? Does it make any other noise or vibrate?

The gas gauge problem is the simplest problem, and actually a pretty common one. The sending unit in the gas tank has a blank spot (for lack of a better word). When the gauge hits that spot, it gets no signal and goes to empty. If it does this for only a certain level of gas, this is the problem. If the level of gas is irrelavent, then it might be related to your other problems.
When the car "cuts out" you say the tach and speedometer quit working. That means you have lost electricity to those parts. I would concentrate on searching for an electrical short. The very first thing I would do is thoroughly clean the battery cables. Electrical problems are the most difficult car problems to diagnose, so, Good Luck.