It does make sense to do firewall forward; it's not something I want to do twice. Thanks guys.

Thanks for the quick reply. This may be a "duh" question but firewall forward includes evaporator, lines, the lot?

Hi. I'm new to this forum and to auto a/c. The system on my '97 Explorer has stopped working. At first the compressor would not engage. When I jumped the low pressure switch the compressor started short cycling: on for a second or two then off for about 4 seconds; on and on. I charged the low side t...