Ok, last night I put some refridgerant in my A/C in my 91 Explorer. Its a 134a system and I filled it up to about 45 psi, this is what is considered "full". Now heres whats odd. When the AC is on, and the pressure is at 45, the compressor kicks on, but as soon as it does, the pressure drops to about 25 and it kicks off. After it kicks off again, the pressure rised back up to 45 again.
I know that AC repair is only to be performed by a tech, and I do NOT intend on doing reapirs myself, but I am going through school for Automotive Service, and I will be taking an AC class, so I am curious what would cause this to happen. I would like to know, and when it does come time to repair, I will either take it in and have it done in class, or take it to the shop and have it repaired. Again, I am NOT attempting to repair this in my garage, I am just curious as to what could cause this, I would like to have an idea before I take it to school or a mechanic.
Thank you
2007-09-02 04:06:40 · 5 answers · asked by ems_fire_rescue_ks 2 in Cars & Transportation ➔ Maintenance & Repairs
you could be over charging the system,remember 134a in a r12 system use less freon,to much freon act just like to little freon,hope that helps.
2007-09-02 07:24:39 · answer #1 · answered by pomohud 5 · 0⤊ 0⤋
OK 45 psi is just enough to activate the low pressure switch and kick on the compressor. You are under charged. Invest in a set of gages. O.K. now had the vehicle been retrofitted over to the R134A. If not here is what needs to be done. First remove the red orifice tube located in the evaporator core next to the fire wall. That will be replace by an orange one. Then take your low pressure switch off and look down into the center of where it pugs in and you will see a screw - turn that one half turn to the left - that will lower your low pressure requirements. Next put on a set of good retrofit valves. Evac the system. Add four to six ounces of pag oil. the system originally held 36 to 40 ounces of R12. Each system is different on retrofits. Start with ambient temperature about 80F or above and put in about 20 or so ounces to start (R134A)(Always load the refrigeran from the low side(blue). Run your air conditioning - the pressures you are looking for are about 30 to 35 psi on the low side and on a ford between 180 - 240 psi on the high side - when you are inside the vehicle put your fan speed on 3/4 and run the rpms to 1500 and you are looking for a vent temp of about 40 degrees. The 3/4 blower fan speed and the 1500rpms simulate your vehicle going 30mph which is what the a/c system is designed for. good luck in your education
2007-09-02 05:41:11 · answer #2 · answered by jack w 4 · 0⤊ 0⤋
Since you didn't vacuum the system down you have some air in the system. It's called static pressure.
2007-09-02 04:17:04 · answer #3 · answered by ryankneale 6 · 0⤊ 0⤋
Plugged up screen in the compressor system.
Just a guess.
2007-09-02 04:15:49 · answer #4 · answered by Mr. KnowItAll 7 · 0⤊ 0⤋
Should it not be topped off with the ac running?
2007-09-02 04:16:16 · answer #5 · answered by David 4 · 0⤊ 0⤋