Converting to R134 on 300E

[Agron80]

Well, its that time of year again--hot and humid. Todays high here in NYC got up to 90F so I naturally had to try the A/C. To my dismay, the system wasnt really blowing "ice cold" air but rather "cool" air. I decided it was time to do the conversion that everyone here talks about and have the A/C system working 100%. Took it into a shop that was referred by my tech and they quoted me $180 for what the shop foreman said "convert to R134 and fully charge the system". I have never done A/C work on any car so I dont know what actually goes into it, and what the going rates are. Does $180 seem excessive to do a complete conversion or am I getting a bargain? Also, what other things should I have the tech check/replace on the A/C system while having the conversion done?? Other than the blower motor squeeling once in a while everything seems fine. Thanks in advance, for this site is truly remarkable.