Tip & How-To about Heating & Cooling

How To Charge Your Vehicle's Air Conditioner

You will need a charging hose with a gauge, and a can or three of R134a refrigerant. Wear eye protection and handle with care.

  1. To begin, you need to adjust the ambient temperature arrow on the gauge to the approximate temperature of the air outside, if possible with your gauge.
  2. Turn on the vehicle, and turn the A/C to high.
  3. Attach the blue charging hose to the low-pressure line, or the bigger of the two metal hoses.
  4. Once attached, check the gauge. If the indicator is in the green area, your system is fine. If it is below the green area, screw on a can of refrigerant and charge the system until the gauge reads in the green.

Steps that a tech will do if you take your car to a shop:

• A temperature sensor is inserted into the AC vent and the system's efficiency is tested.
• The high-pressure side of the system is connected to the recycling-recharging testing machine, then the low-pressure side.
• The machine reclaims and stores the refrigerant. The system is then run under a vacuum for 30 minutes to test for leaks. This process also removes accumulated moisture.
• If all is well, the refrigerant is reintroduced into the system, and topped off as required.
• The sight glass on the evaporator is literally a window into the AC system. If the window is not clear, or bubbles are visible, this can indicate system trouble.

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1 Answer

my a/c needs charged. where is the port to hook up the 134a hose. The one by the right front headlight is too big for the coupler i have


The a/c refrigerant should be charged up using the low side port hose of the vehicle's a/c system, this hose is usually the bigger one which is the low side. never recharge the a/c system using the smaller port hose (the high side) because it can blow up your freon can and cause bodily injury. always wear eye goggles for protection when installing freon.

Mar 19, 2011 | 1994 Ford Taurus

1 Answer

where is the low pressure ac valve?


FOLLOW THE REFRIGERANT LINE LEADING FROM AC COMPRESSOR TO EVAPORATOR TO THE BACK FIREWALL LOOK FOR REFRIGERANT LINE WITH BLACK OR BLUE CAP THATS LOW PRESSURE SUCTION SIDE..WHEN HANDLING REFRIGERANT WEAR SAFETY GOGGLES TO KEEP REFRIGERANT GETTING INTO YOUR EYES.WHICH CAN CAUSE BLINDNESS OR DAMAGE EYES.YOU NEED A LOW AND HIGH PRESSURE GAUGE.OR MANIFOLD GAUGE SET.LOW SIDE PRESSURE SHOULD BE 28 PSI AND HIGH SIDE SHOULD BE 200 - 220 PSI.

Feb 20, 2011 | 1991 Mazda 626

1 Answer

How do you connect a/c charger to make your central air cooler


The 1998 Dodge Caravan ac should be charged at the low pressure service port. This port is located on the suction line near the compressor. The suction line can be identified by it's size, it being the larger of the two line connected to the compressor. You must purchase a recharge kit at your local part store, which should include charging hose with pressure gauge and a can of R134a freon. Gloves and eye protection should be worn during servicing.(freon can freeze your eyes and cause frost bite to your hands). Connect freon to charging hose, connect charging hose to low pressure service port, open valves and start engine, turn on ac. If compressor won't start it may be required to disconnect the low pressure switch and jump out the connector.

Jul 16, 2010 | 1998 Dodge Caravan

1 Answer

I can't locate the low valve on my 1991 ford explorer engine to install freon


Wear eye protection before you do this. Follow the a/c line from firewall to compressor there should be a low side schrater valve there for charging. This vehicle uses R12, this refrigerant is expensive.( unless it has been converted to R134A). I recommend you check for leaks before charging it and use the correct manifold gauge set to do it with.

Jun 21, 2010 | 1991 Ford Explorer

1 Answer

how can i recharge the air conditioner? Where is the hose located?


Ok if you want to do a home repair in hopes of saving yourself a lot of money and with hopes your system is not in major trouble, here goes:
First step buy 3 types of 1 lb. cans of refrigerant R134a at a parts store, 1 can of leak detector freon combination, and if possible 1 can freon/air conditioning oil combination freon along with 1 can of straight r134a freon.
The store will sell you a charge hose with a cheap type of charge gauge attachment and fittings to attach to your system for the re-charge.
Providing your system is low on freon,First, with the vehicle running and the a/c on full cold, high fan, install the 1 lb. can of freon/oil combo first only charging through the low pressure side of the system never through the thin line high pressure side as the pressure from the high side can enter the cgharging freon can and explode it like a bomb,(this low side line is the larger hose and the low side charging hose fitting the parts store sells you will only screw onto the low side charge valve which is normally marked "low" on the top of the plastic dust cap that is factory installed(hand screwed) on the low side valve fitting.
Secondly after the oil/combo can is emptied into the low side and you of course are wearing mechanics hand protection gloves and eye protection googles, then and only then will you install the leak dector 1 lb. freon can combo.
Third you will install the last 1 lb can of r134a freon, however your vehicle will not allow the whole last pound of freon into its system by means of a pressure relief blow valve that will automatically blow off any excess pressure once the system over fills, the system typically holds approximately 2.75 lbs. of freon.
If you have successfully installed the above freon into the system it should be up and running providing the system is in fairly good working order, by that I mean it may have a very slow leak that allowed the freon tio originally escape in the first place causing you to refill it, and if it does have a leak the leak detector die that you installed into the system should leak out from wherever it may be escaping from, indicating the place of needed repair by means of a red or blue, or whatever other designated coloration the die gives out from the leaking area.
Please note: Not all home charging techniques typically work as there are many mechanical failure factors in an a/c system that may require a certified a/c technician to determine exactly why your system is not working should the home remedy fail.
I hope this helps you and remember to always work safe with eye and hand protection especially around freon gases which become extremely cold and can cause frost bite when contacting with the bare skin.

May 08, 2010 | 2001 Cadillac DeVille

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