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Machinery Forum Re: Re: Re: JD 6200 A/C question [ Expand ] [ View Follow Ups ] [ Post Followup ] [ Return to Forum ] Posted by greg on September 27, 2003 at 16:37:58 from (66.153.10.236): In Reply to: Re: Re: JD 6200 A/C question posted by Lynn on September 04, 2003 at 19:08:38: R134a will commonly run higher pressures than most people are used to with r-12. Sounds to me like it may have been slightly overcharged, creating a high pressure situation. Ambient temp is a great factor in determining operating pressures. A/C works off a temp/press relationship-if ambients are high, system will go high. I would think if you recovered and sucked down (vacuumed) the system and recharged with a new drier, clean oil, etc, it should recharge and work well. I have good luck converting 12 to 134 by 1) vac system. 2) see if system will maintain vac after vac pump is turned off for 10 minutes. 3) replace drier. 4) vac again for half hour. 5) Fresh oil charge. 6) Charge untill acceptable duct temps are realized. (I charge vapor in low side slowly, monitoring duct temps all the while, this can take quite a few minutes but I have good luck with it. Only after I am satisfied with duct temps do I check sight glass. Many systems do not have sight glass anymore.) If you are retro'ing to 134, system capacity is only 85% of what the r12 capacity was by weight. Many of the old R12 systems had overheat safety temp and pressure switches that wouldn't relieve until 400 degrees F and/or 400 psi- some even higher!!! I don't find your pressure readings reason for alarm, depending on your ambients. Good luck. Follow Ups: Post A Followup Name: E-Mail: Subject: Re: Re: Re: Re: JD 6200 A/C question Comments: Optional Link URL: Link Title: Optional Image URL: Email Notification: If you check this box, email will be sent to you whenever someone replies to this message. Your email address must be entered above to receive notification. This notification will be cancelled automatically after 2 weeks.