Chrysler Repair: AC suddenly quit in van, check engine light on, powertrain control module, dodge grand caravan

Question
Hello! I have a 2000 Dodge Grand Caravan. It's high mileage but has always ran great. That is until my husband hit a deer a few months back! We had it repaired by a reputable shop--most of the front end components were replaced. Radiator, condenser, fans, etc. Well, it started overheating, so I took it back to the shop. They replaced a fan relay, and all was well again. While they were working on it, I saw them put some refrigerant in for my ac. It had been working fine, so I don't know why they did it. I've only ran the ac a few times since then, and it was fine. Tried to turn it on last weekend, and it will no longer blow cold air. The check engine light also came on a few days ago and is staying on. (Used to come on intermittently, was told it was emissions-related) Are any of these things related? What should my first steps to identifying the problem be? I dread a huge repair bill after I've already spent almost $3000 to have the van repaired. Thanks!

Answer
Hi Emily,
The most common reason for the AC not coming on and thus producing no cool air is that refrigerant has leaked sufficiently to open the pressure switch which prevents the clutch from engaging the compressor so it won't be damaged. I would want to check that possibility out and if so try to locate the leak in the system which may be related to the accident and/or an imperfect repair at a joint or connector of the piping for the refrigerant. That might be a basis for getting reputable shop to repair something didn't do right or overlooked about that system.
On the check engine light, I would seek a readout of the fault codes stored in the powertrain control module which is synonymous with the light being "on". You often can get that done for free at an Autozone parts store or for maybe $40 at an independent shop offering a "special". Find out the fault code numbers (4-digit) what they mean and what they propose needs to be done. Then if you like write me back and we'll compare their report to what it says in the manual. Let me know which engine size is in your van as the repair may be different for each.
Roland